Release 1.0 – September 2006 1 Radio and Electricity Radio works because of electricity, so to...

1Release 1.0 – September 2006

Radio and Electricity

Radio works because of electricity, so to understand radio, you have to know a little bit about electricity. In this group, we’ll get some of the basics of electricity out of the way. There are three units we will study related to electricity in this group – voltage, current, and power. By the time you are ready for your test, you will be very familiar with all of them.


Static Electricity

If you have ever shuffled across a carpet and touched a doorknob on a cold dry day, you probably got a nice little shock.

You probably also heard the crackle of an electric spark at your fingertip. If the room was dark, you may have even seen the spark. You may have seen the same thing when you combed your hair, pulled off a sweater, or slid across a cloth car seat.

This is called static electricity.


The Source of Static Electricity

To understand where static electricity comes from, we first have to learn (or review) just a little bit of chemistry.

All the stuff around us – solids, liquids and gases – is called “matter.” All matter is made of extremely tiny particles called “atoms.” Atoms are far too small to be seen, even with the best microscopes, but we still know quite a bit about them.


The Helium Atom

Take a look at the helium atom. It has two protons and two neutrons in its nucleus, with two electrons spinning around the nucleus.


AtomsLike the helium atom, all atoms are made of

a tightly packed center called a “nucleus” that is made up of even smaller particles called “protons” and “neutrons.” The proton has a positive charge and the neutron has a neutral charge. Buzzing around this nucleus of protons and neutrons are particles that are many times smaller than even the protons and neutrons. These particles are called “electrons” and have a negative charge. Electrons circle around the nucleus in paths that are called “orbits.”

Don’t worry too much about all this charge business just yet, but do try to remember that protons have a positive charge, electrons have a negative charge, and neutrons have a neutral charge


Kinds of Atoms

The number of protons in an atom determines what kind of atom it is. For example, a copper atom, shown here in diagram form, has exactly 29 protons represented by the “+” in the nucleus or center. A typical copper atom will also have 34 neutrons, but that number can vary. The 29 protons are matched by 29 electrons in the shells or orbits surrounding the nucleus.


Electron Charges = Static Electricity

A long time ago, people figured out that if you rubbed certain substances together - such as fur and rubber - a charge would be produced, just like the charge produced by your shuffle across a carpet on a cold day.


Electron Charges

It turns out that this charge is simply a bunch of loose electrons that have no place to go. In some atoms, electrons are not held very tightly and can easily be removed. When a rubber rod is rubbed with fur, electrons are removed from the fur and build up on the rubber rod as static electricity.


Static Electricity

So static electricity is just a bunch of electrons looking for some place to go. When you shuffle across a carpet, you pick up loose electrons. When you get to a metal doorknob, these electrons are attracted to that metal and – ZAP!


Cute, But No Good For Radio

Static electricity is interesting to play with. It’s fun to shock someone else instead of the doorknob. (Come on, admit it. You know you’ve done that!) It is also interesting to see the sparks fly when you pull off your sweater in a darkened room. And it is really cool to watch the ultimate static electricity spark – a lightning bolt!

However, static electricity is no good for radio. So why did we bother with it? Because you need to understand that electricity is electrons. Let me say that again. Electricity is electrons!

So let’s get on to electricity we can use!


The Humble Flashlight

A simple flashlight is nothing more than a bulb, one or more batteries, and a switch to turn it on or off.


Inside the Flashlight

Look inside the flashlight and you will see that the end of the bulb tip touches the tip of one battery, and that the side of the bulb touches metal – usually the metal reflector. This reflector comes in contact with the switch. If you look carefully, you will see that the this switch is connected to the bare metal spring at the bottom of the flashlight, and that spring touches the bottom of the other battery. Finally, the tip of the bottom battery touches the bottom of the top battery.


Flashlight – Schematic Diagram

If you diagram the flashlight, it looks something like this:


Schematic DiagramNotice the symbols that are used to represent the

switch, bulb and batteries. These are “schematic symbols.”

Also notice that there is a continuous loop from the bulb to the switch to the batteries and back to the bulb. This loop is called a circuit.

When the switch is open, the circuit is broken. We call that an “open circuit.” When the switch is closed, there is an unbroken loop. We say that the circuit is now “closed” because of this unbroken loop.

When the circuit is closed, electricity can begin to move through this closed loop from the batteries, through the bulb, through the closed switch, and back to the batteries at the other end.


Simple Light Circuit This may be a little bit easier to see if we

connect everything together with wires. Here you see a bulb from a Christmas tree light set connected to two batteries and a crude switch. As pictured, the switch is open and the light is off.


Simple Light Circuit

Press the switch and the light comes on.


So what’s Happening?When you press the switch, the circuit is

closed and electricity (electrons) begins to flow from the negative (-) end of the battery where they are stored up, through the wire loop to the bulb, and back into the positive (+) end of the other battery where the battery is hungry for all those extra electrons. As the electricity flows through the bulb, some of the energy of this flow lights up the bulb.

Unlike static electricity, which is just a bunch of electrons that will jump ship and make a spark at the first chance they get, this kind of electricity is a nice flow of electrons through a circuit that can actually do some useful work.


ConductorsSome substances, including most metals,

provide an easy path for electrons to move through them. Any substance that allows electrons to flow freely through it is called a “conductor.” One excellent conductor is copper. Shown below is a piece of stranded copper wire. (“Stranded” means that the wire is actually made up of a number of smaller wires twisted together.)


InsulatorsOther substances do not allow electrons to

flow through them. They are called “insulators.” One excellent electrical insulator is glass. Other insulators include rubber, wood and plastic. Insulators, such as the black plastic shown here surrounding the copper wire, helps to prevent electric shock by not allowing electrons to pass through.


Current

Now with all of that information, here is the first big idea. This orderly flow of electrons in an electric circuit is called current. It is this electric current that is the workhorse of radio and electronics!


Current Is Measured In Amperes (Or Amps)

We need to measure just how much current we have flowing through a circuit. Electrical current is measured in a unit called amperes. This unit is often abbreviated to “amps.”


How Do We Measure Amps?

The instrument used to measure the flow of current in an electrical circuit is called an ammeter. The one shown here measures in “milliamperes” (milliamps) or thousandths of an ampere


Voltage and Volts

Sometimes we need to know just how hard current is being pushed through a circuit. Imagine a water hose, and imagine that the water in that hose is like electrons flowing through a wire. Now suppose this hose passes a gallon of water every minute. If you squeeze the hose, it will still pass the same amount of water, but it will pass it out in a smaller and sharper stream. You haven’t changed the amount of water flowing, but you have changed the pressure.


Voltage and Volts

Electric current is like that as well. Without changing the number of electrons flowing in the circuit, we can change the pressure on those electrons. The pressure placed on those electrons is called “voltage.” It is also sometimes called “electromotive force” or “EMF.” Regardless of what it is called, it is measured in units called “volts.”


How Do We Measure Volts?The instrument

used to measure Electromotive Force (EMF) (or voltage) between two points such as the poles of a battery is called a voltmeter.


BatteriesWe often see

batteries measured in volts. A typical AA, AAA, C or D cell produces an electrical pressure of about 1.5 volts. If the cells are stacked together “+” end to “-“ end, we can add their voltage. So the total voltage in our flashlight, as well as the simple light circuit, was about three volts.


Batteries for Hams

The most useful battery for hams for field work is the automobile battery because it can supply the voltage needed for most amateur radios we might want to run in our vehicles. The typical automobile battery usually supplies about 12 volts.


Gel Cell Rechargeables Today, many hams also use high capacity 12

volt “gel cell” batteries such as the one shown here. They are relatively inexpensive, but care must be taken to charge them properly!


Power - Watts

We still have a few more terms to go. We measure the total electric power used or produced with a unit called “watts.” One good example is the light bulb. Light bulbs are classified based on the number of watts they use. (This also gives some indication of how bright the bulb will be. We’ll learn more about power in a bit, but for now, remember that electrical power is measured in watts.


“Resistance Is Futile!”

Only if you are the Borg! In electricity, resistance is very useful. Consider our simple light circuit. When electricity flows through a metal wire, the electrons zip along with very little to slow them down. But when these electrons hit something like the tiny filament inside a bulb, it resists the flow of these electrons. This resistance changes some of the electrical energy into the light we wanted in the first place.


Resistance - Ohms

There are some materials, such as the filament in the light bulb, that oppose current flow. The term used to describe opposition to current flow is called resistance.

This resistance can also be measured, and it is very useful to do so. The basic unit of resistance is the ohm.


The Multimeter

For the Technician exam, you have to know that the ammeter measures current (amps), and the voltmeter measures electromotive force (or voltage). You do not have to know that the ohmmeter is used to measure resistance. Actually, all three of these can be measured with a single meter called a “multimeter.” A good multimeter is very inexpensive and extremely useful to have around.


The Multimeter

Here is a typical multimeter that will measure voltage, current and resistance. It costs less than ten dollars, and is a very useful tool that no ham should ever be without!


Direct Current

In our simple light circuit, electricity leaves the batteries from one end, flows through the wire in one direction, and enters the other end of the batteries. In other words, the electron flow (or current) is in one direction only. Current that flows only in one direction is called direct current, and is abbreviated DC.


Alternating Current Electric current in your home works almost

the same way, but not quite. Because of the way household electricity is produced, it does not flow in the same direction all the time. In fact, it is constantly reversing direction. As far as doing useful work, it doesn’t matter whether the electrons are moving in the same direction all the time or constantly changing direction. As long as the electrons are moving, the work will get done.

When an electric current reverses direction on a regular basis, it is called alternating current, and it is abbreviated AC.


Representing AC

We can represent the flow of alternating current using a wavy line like this one, called a sine wave. (Don’t worry about why it’s called a sine wave. There’s a good reason, but you don’t need to know it for the Technician test.)


An Electron Roller Coaster

Now imagine a tiny electron riding along this sine wave, kind of like a roller coaster. When the electron goes up the curve, it is traveling in one direction. When it goes back down the curve, it has reversed itself and is traveling in the opposite direction.


Cycle

Let’s say we start at the point on the roller coaster labeled “A” and time how long it takes for the electron to get to “B” on the roller coaster. If you look carefully, you’ll see that the electron went up, then all the way down, and all the way back up. In other words, it went through one complete curve of this roller coaster. We call this complete trip down in one direction and all the way back in the other “one cycle”


Frequency

With any good roller coaster ride, the faster the better! So let’s suppose we want to measure how fast our little alternating current electron is going up and down this roller coaster. We want to know how many times our electron is reversing directions in one second. If we time the reverses of direction in U.S. household alternating current, it turns out that it reverses about sixty times per second. Since each complete reversal is one cycle, we say that alternating household current reverses at sixty cycles per second.


Frequency Definition

Frequency is the measure of the number of cycles per second an alternating current reverses. It is measured in a unit called the hertz. One hertz is equal to one cycle per second, and the Hertz is the standard unit of frequency.

Based on this, the AC current in a U.S. household is 60 Hertz.

Whew! That was a lot of stuff to remember. If you are not sure you understand it, go back over this section until you do.


Check-Up Time!

Now let’s try the questions from this group.

You should make a note of any that you miss for later review.


T4A01

Electrical current is measured in which of the following units?

A. Volts

B. Watts

C. Ohms

D. Amperes


T4A01 Answer - D

Current is measured in amperes (or more commonly amps). It is a measure of the amount of electrical energy. Power supply capacity is often rated by the number of amps it can produce at a given voltage.


T4A02

Electrical Power is measured in which of the following units?

A. Volts

B. Watts

C. Ohms

D. Amperes


T4A02 Answer - B

Overall electrical power is generally measured in watts. Transmitter power output is often measured in watts. So are many common home appliances and light bulbs.


T4A03

What is the name for the flow of electrons in an electric circuit?

A. Voltage

B. Resistance

C. Capacitance

D. Current


T4A03 Answer - D

Current is the amount of electron flow in a circuit. The greater the amount of electron flow, the higher the current.


T4A04

What is the name of a current that flows only in one direction?

A. An alternating current

B. A direct current

C. A normal current

D. A smooth current


T4A04 Answer - B

Direct current flows through a circuit in one direction only.


T4A05

What is the standard unit of frequency?

A. The megacycle

B. The Hertz

C. One thousand cycles per second

D. The electromagnetic force


T4A05 Answer - B

The basic unit of frequency is the Hertz. One Hertz equals one cycle per second.


T4A06

How much voltage does an automobile battery usually supply?

A. About 12 volts

B. About 30 volts

C. About 120 volts

D. About 240 volts


T4A06 Answer - A

Most amateur equipment is designed to be powered by a 12 volt supply. This is so primarily because most car batteries are 12 volt batteries.


T4A07

What is the basic unit of resistance?

A. The volt

B. The watt

C. The ampere

D. The ohm


T4A07 Answer - D

Resistance is the opposition to current flow and it is measured in ohms. Whenever electricity passes through a wire or any other component and it either begins to glow or generate heat or both, that is due to resistance.


T4A08

What is the name of a current that reverses direction on a regular basis?

A. An alternating current

B. A direct current

C. A circular current

D. A vertical current


T4A08 Answer - A

Alternating current flows first in one direction and then in the opposite direction, usually in a very regular cycle. The alternating current in U.S. households changes direction 120 times per second. Each two changes in direction (down and back up) is one cycle, creating 60 complete cycles every second, so we say that electric current has a frequency of 60 cycles per second or 60 Hertz.


T4A09

Which of the following is a good electrical conductor?

A. GlassB. WoodC. CopperD. Rubber


T4A09 Answer - C

Metals are generally good conductors of electricity. A conductor is a substance that allows electrons to flow through it easily.


T4A10

Which of the following is a good electrical insulator?

A. Copper

B. Glass

C. Aluminum

D. Mercury


T4A10 Answer - B

Non-metals do not allow electrons to move through them very readily, so they make good insulators.


T4A11

What is the term used to describe opposition to current flow in ordinary conductors such as wires?

A. InductanceB. ResistanceC. Counter EMFD. Magnetism


T4A11 Answer - B

Even the best conductors offer some resistance to current flow, but this resistance is not enough to make much difference unless the conductor is very long, such as a long strand of wire.


T4A12

What instrument is used to measure the flow of current in an electrical circuit?

A. Frequency meter

B. SWR meter

C. Ammeter

D. Voltmeter


T4A12 Answer - C

If you remember that current is measured in amps, the answer to this question should be easy!


T4A13

What instrument is used to measure Electromotive Force (EMF) between two points such as the poles of a battery?

A. MagnetometerB. VoltmeterC. AmmeterD. Ohmmeter


T4A13 Answer - B

Electromotive force is the fancy name for voltage, and voltage is measured with a voltmeter.


Group T4B

Group T4B covers the relationship between frequency and wavelength, identification of amateur radio bands, names of frequency ranges,

and types of radio waves .


Radio Waves

Radio waves are a kind of energy that carries your voice and data from your transmitter to another ham’s receiver. We can’t see a radio wave, but we don’t have to actually see it to understand it.

Remember our electron roller coaster,

better known as a sine wave? It turns out that a sine wave is a pretty good model to explain radio waves, so let’s take a closer look.


Waves

If you have ever dropped a stone into a pool or pond, you know what happens. You get a series of ripples that spread out in circles. The energy from that falling rock is transferred to the water and spreads out in the form of these little ripples or waves.


Waves – A Closer Look


Wave Form

If you look at the cross section of the waves on the diagram in the previous slide, you can see that it looks a lot like our sine wave. That’s because it is a sine wave, and you can imagine the moving curve as the waves spread out from where the stone was dropped. Unlike our electron roller coaster, it is the wave that moves, and not something moving along the wave.


Wavelength

Here is a plain sine wave. If we measure from Point A to Point B, the distance is the length of one complete wave or cycle. We call this the wavelength. The name for the distance a radio wave travels during one complete cycle is wavelength.


Frequency

Remember that the frequency of alternating current is a measure of the number of cycles per second that alternating current reverses. So the number of times that an alternating current flows back and forth per second is its frequency.


Measuring Frequency

As you saw in the last group of questions, frequency is measured in a unit called the Hertz. Hertz is the standard unit of frequency, and one hertz is equal to one cycle per second.

Since the frequency of AC house

current is 60 Hertz, we say it goes through 60 cycles per second.


Radio WavesNow 60 cycles per second (or 60 Hertz) seems

pretty fast. But imagine the ripples on the pond moving out at a speed of 20,000 times a second. That’s 20,000 waves lapping up against the shore every single second.

Obviously, water waves cannot do that, but radio waves can. They are waves of energy that act a little like electric waves, and a little like magnetic waves. Radio waves are types of waves known as “electromagnetic waves.” Radio waves “oscillate” (or reverse direction) at a frequency of at least 20,000 Hertz.

Electromagnetic waves that oscillate more than 20,000 times per second as they travel through space are generally referred to as radio waves.


How Fast Do Radio Waves Move?

If radio waves oscillate more than 20,000 times a second, just how fast do they move? It turns out they move pretty darn fast. In fact, radio waves travel through space at the speed of light. And in case you didn’t know, the speed of light is (approximately) a whopping 186,000 miles per second. At that speed a light beam will cover a distance equal to over seven times around the world in less than a second!


Wavelength, Frequency and the Speed of Light

The wavelength and frequency are directly related to each other and to the speed of light. We won’t bore you with the stuff you don’t need to know about that. However, there are some things you are going to have to know to understand this stuff, so let’s get to it.


Wavelength RevisitedTake another look at the diagram of the sine

wave. You should remember that the distance from Point A to Point B is the wavelength. In the radio world, wavelength is measured in meters.


Frequency Revisited

You should also remember that the frequency of a wave is the measure of the number of cycles it completes in one second. One cycle per second is one Hertz.

But we saw that the lowest frequency of a radio wave is 20,000 Hertz, and it goes way up from there. Radio wave frequencies can go into the millions of Hertz!


So how do we Handle the Big Numbers?

Let’s take the lowest frequency radio wave at 20,000 Hertz. It is sometimes easier to use larger units to deal with numbers as large as this. In the radio business, we use two different units to help us deal with large numbers.


Kilohertz (KHz)

The first unit we use is the “kilohertz.” One kilohertz is equal to 1000 Hertz. Kilohertz is abbreviated “KHz.”

Using this unit, 20,000 Hertz equals 20 Kilohertz (or 20 KHz).

It may not be any simpler, but it is a little shorter.


Megahertz (MHz)When the frequency of a radio wave gets into

the millions, the numbers get really big. One popular amateur band, the 2 meter band, starts at a frequency of 144,000,000 Hertz. As you can see, 144 million is a pretty large number, so we use our second unit to make things a little easier to manage.

So the second unit we use is the “megahertz.” One megahertz equals 1,000,000 Hertz. Megahertz is abbreviated “MHz.”

Using this unit, 144,000,000 Hertz becomes 144 megahertz (or 144 MHz).


Is Your Head Spinning Yet?

We promised we would explain a little more about the amateur bands, so here goes. You now know that the 2 meter band begins at 144 MHz. Do you know why the call it the 2 meter band?

Here’s a hint. Remember that the wavelength of a radio wave measured in meters.


Aha!That’s right! This band is called the 2

meter band because 2 meters is the approximate wavelength of the waves in this band.

That’s the same reason we call the other ham bands what we do. The 6 meter band has radio wavelengths of about 6 meters, the 1.25 meter band has radio wavelengths of about 1.25 meters, and the 70 centimeter band has radio wavelengths of about .7 meters. (Sneaked that last one in on you, didn’t we?)

So remember that the property of a radio wave often used to identify the different bands amateur radio operators use is the physical length of the wave, or simply the wavelength


Formulas to Forget

OK, we’re going to give you two formulas that show you how frequency and wavelength are related, and here they are...

300Wavelength (in meters) = -----------------

Frequency (in MHz)

300Frequency (in MHz) = ---------------------

Wavelength (in meters)


What’s Important!

These two formulas show the math whizzes among us what the rest of us will just have to memorize. The wavelength of a radio wave relates to its frequency in that the wavelength gets shorter as the frequency increases, and the wavelength gets longer as the frequency decreases. The same is true for frequency.


Frequency Ranges of Several Bands

OK, now that you know all about how frequency and wavelength are related, and you also know that amateur bands are often described by their average wavelength, it’s time to learn some really useful stuff. Below are the frequency ranges of several ham bands that you can use as a Technician. There’s no way around it, you’ll need to memorize them to “ace” the exam!

Frequency range of the 2 meter band in the U.S. - 144 to 148 MHz

Frequency range of the 6 meter band in the U.S. - 50 to 54 MHz

Frequency range of the 70 centimeter band in the U.S. - 420 to 450 MHz


Sound WavesSound also travels in waves, but unlike

radio waves, sound waves cannot travel through space. Sound waves can only travel through air or some other type of matter. However, like radio waves, sound waves also have a range of frequencies as well.

Generally, the higher the frequency, the

higher pitched the sound.

Sound waves in the range between 300 and 3000 Hertz are the frequencies of the average human voice. These frequencies are important because hams are trying to transmit their voices all the time, and they want to use microphones that have a good frequency response in the human voice range.


Check-Up Time!




T4B01

What is the name for the distance a radio wave travels during one complete cycle?

A. Wave speed

B. Waveform

C. Wavelength

D. Wave spread


T4B01 Answer - C

The distance a radio wave travels in one cycle is its wavelength. Amateur bands are often identified by the average wavelength of the radio waves within that band, such as the 2 meter band, or more often, just "2 meters."


T4B02

What term describes the number of times that an alternating current flows back and forth per second?

A. Pulse rate B. Speed C. Wavelength D. Frequency


T4B02 Answer - D

Frequency is the number of times an alternating current, such as a radio wave, travels back and forth in one second. Each cycle is one Hertz. In the case of AC house current, the frequency is relatively low – only 60 cycles per second.

However, as you will soon see, the frequencies of radio waves are much higher, and depending on the frequency, they are measured in either kilohertz (1000 hertz) or megahertz (1 million hertz).


T4B03

What does 60 hertz (Hz) mean?

A. 6000 cycles per second

B. 60 cycles per second

C. 6000 meters per second

D. 60 meters per second


T4B03 Answer - B

Hertz means "cycles per second."


T4B04

Electromagnetic waves that oscillate more than 20,000 times per second as they travel through space are generally referred to as what?

A. Gravity waves

B. Sound waves

C. Radio waves

D. Gamma radiation


T4B04 Answer - C

Radio waves are waves of electromagnetic energy that have a frequency of more than 20,000 hertz (or 20 kilohertz). An electromagnetic wave is a wave of energy with electrical and magnetic components.


T4B05

How fast does a radio wave travel through space?

A. At the speed of lightB. At the speed of soundC. Its speed is inversely proportional to its wavelength

D. Its speed increases as the frequency increases


T4B05 Answer - A

All electromagnetic waves travel through space at the speed of light - about 186,000 miles per second!


T4B06

How does the wavelength of a radio wave relate to its frequency?

A. The wavelength gets longer as the frequency increases

B. The wavelength gets shorter as the frequency increases

C. There is no relationship between wavelength and frequency

D. The wavelength depends on the bandwidth of the signal


T4B06 Answer - B

As frequency increases, the wavelength gets shorter. As frequency decreases, the wavelength gets shorter. For you math whizzes, frequency and wavelength are inversely proportional. (No, that’s not on the test.)


T4B07

What is the formula for converting frequency to wavelength in meters?

A. Wavelength in meters equals frequency in Hertz multiplied by 300

B. Wavelength in meters equals frequency in Hertz divided by 300

C. Wavelength in meters equals frequency in megahertz divided by 300

D. Wavelength in meters equals 300 divided by frequency in megahertz


T4B07 Answer - D

300

Wavelength = ---------------

(Meters) Frequency (MHz)


T4B08

What are sound waves in the range between 300 and 3000 Hertz called?

A. Test signals

B. Ultrasonic waves

C. Voice frequencies

D. Radio frequencies


T4B08 Answer - C

Knowing where the voice frequencies are concentrated is very useful when adjusting for the best possible audio from your microphone.


T4B09

What property of a radio wave is often used to identify the different bands amateur radio operators use?

A. The physical length of the waveB. The magnetic intensity of the waveC. The time it takes for the wave to travel one mile

D. The voltage standing wave ratio of the wave


T4B09 Answer - A

Amateurs often refer to the various bands by their approximate wavelength, such as 80 meters, 20 meters, 10 meters or 2 meters.


T4B10

What is the frequency range of the 2 meter band in the United States?

A. 144 to 148 MHz

B. 222 to 225 MHz

C. 420 to 450 MHz

D. 50 to 54 MHz


T4B10 Answer - A

You will almost certainly get at least one question on your exam about the frequency of a particular band or sub-band. The bad news is they just have to be memorized. The good news is that this is information you will use as long as you are a ham.


T4B11

What is the frequency range of the 6 meter band in the United States?

A. 144 to 148 MHz

B. 222 to 225 MHz

C. 420 to 450 MHz

D. 50 to 54 MHz


T4B11 Answer - D

Next to 2 meters, 6 meters is probably the most popular band for Technician licensees. When this band is open, you can work some real DX (long distance contacts)!


T4B12

What is the frequency range of the 70 centimeter band in the United States?

A. 144 to 148 MHz

B. 222 to 225 MHz

C. 420 to 450 MHz

D. 50 to 54 MHz


T4B12 Answer - C

There are really only three bands you’ll need to know the frequencies for – 6 meters, 2 meters, and 70 centimeters. They are important to you because they are all bands open to you as a Technician licensee.


Group T4C

Group T4C covers how radio works. It also covers receivers, transmitters,

transceivers, amplifiers, power supplies, and types of batteries and

their service life .


Radio Equipment

After all of that heavy theory about radio waves, we’re going to take a look at some very basic information about what different radio components do.


Radio Receiver

The radio receiver is a device used to convert radio signals into sounds we can hear. You should be very familiar with radio receivers. You use them to listen to your favorite radio stations. The receivers hams use do the very same thing, except we use them to listen to other hams.


Radio Transmitter

A radio transmitter is used to convert sounds from our voice into radio signals that are then sent out over the air to the other ham’s radio receiver.


Transceiver

Back in the early days of amateur radio, every ham had to have two separate pieces of equipment – a transmitter and a receiver. The transmitter was used to generate the signal sent out over the air, and the receiver was used to receive the other ham’s signal. However, for many years now, the transmitter and receiver have been combined into a single unit called a transceiver


Transceiver

In a transceiver, the transmitter and receiver are combined into a single unit. This eliminates the need for having to have the two separate units and it makes tuning much easier as well.


Power Supply

Most modern radios require 12 volts DC as a power source. This allows them to be operated mobile using car batteries. The voltage coming from the plugs in U.S. homes is 110-120 volts AC. To get the proper voltage to use these radios in your home, you need a device called a “power supply.” The power supply is a device is used to convert the alternating current from a wall outlet into low-voltage direct current. The output of a power supply used for amateur radio is usually about 12 volts.


RF Amplifier

Sometimes a ham may need or want more output power than the radio is capable of generating. An RF (radio frequency) amplifier is used to increase the output of a radio to a higher power. For example, you could use an amplifier to boost the power of a 10 watt radio to 100 watts.


Batteries

Most handhelds are powered by batteries, and there are a number of different types. For example, there are lead-acid batteries, alkaline batteries, nickel-cadmium batteries and lithium-ion batteries. Of these, the lithium-ion battery offers the longest life when used with a hand-held radio, assuming each battery is the same physical size. You probably already know this if you use a digital camera.


Nickel-Cadmium BatteriesMost fully charged AA, AAA, C or D batteries

have a charge of about 1.5 volts. However, a fully charged nickel-cadmium battery has a nominal voltage per cell of about 1.2 volts. This voltage is lower than most other types of batteries, but the advantage of a nickel-cadmium cell is that it is relatively inexpensive and rechargeable, and that can save a lot of money.


Carbon-Zinc Batteries

Carbon-zinc batteries are the common AA, AAA, C or D batteries you find at the local store. They are usually the most inexpensive batteries, but they have one distinct disadvantage that makes them fairly expensive in the long run. Unlike nickel-cadmium, lead-acid or, lithium-ion batteries, carbon-zinc batteries are not designed to be re-charged.


Battery Care As a Technician, you will almost certainly

use some sort of rechargeable batteries with your equipment. Regardless of the type of rechargeable you use, there are several things you should do to keep rechargeable batteries in good condition and ready for emergencies.

They should be inspected for physical damage

and replaced if necessary

They should be stored in a cool and dry location

They must be given a maintenance recharge at least every 6 months


Battery Use

Regardless of the kind of battery you use, the best way to get the most amount of energy from a battery is to draw current from the battery at the slowest rate needed. This will help your battery to last much longer.


Check-Up Time!




T4C01

What is used to convert radio signals into sounds we can hear?

A. Transmitter

B. Receiver

C. Microphone

D. Antenna


T4C01 Answer - B

Radio signals are received and changed into sound by a receiver. Radio signals are produced by a transmitter. When the transmitter and receiver are combined into a single unit, as is almost always the case with modern radios, the combination is called a transceiver.


T4C02

What is used to convert sounds from our voice into radio signals?

A. Transmitter

B. Receiver

C. Speaker

D. Antenna


T4C02 Answer - A

Radio signals are produced by a transmitter. Radio signals are received and changed into sound by a receiver. When the transmitter and receiver are combined into a single unit, as is almost always the case with modern radios, the combination is called a transceiver.


T4C03

What two devices are combined into one unit in a transceiver?

A. Receiver, transmitter

B. Receiver, transformer

C. Receiver, transistor

D. Transmitter, deceiver


T4C03 Answer - A

In the early days of amateur radio, even up to the 1960s, the transmitter and receiver were usually two separate units. However, beginning in the mid 1960s, the two units were combined to make a transceiver. Almost all commercially produced amateur gear is of the transceiver type, with the exception of a few simple kits.


T4C04

What device is used to convert the alternating current from a wall outlet into low-voltage direct current?

A. InverterB. CompressorC. Power SupplyD. Demodulator


T4C04 Answer - C

Most amateur gear requires 12 volts direct current (DC). When amateur gear is used in the home, a power supply is required to convert the 110 volt alternating current (AC) from the wall socket to the 12 volt direct current (DC) required (or any other DC voltage that may be required).


T4C05

What device is used to increase the output of a 10 watt radio to 100 watts?

A. Amplifier

B. Power supply

C. Antenna

D. Attenuator


T4C05 Answer - A

An amplifier is a device that is used to amplify or increase the power of a signal. An amplifier may be used to increase RF (radio frequency) power. Other amplifiers may be used to increase the power of a sound signal such as a guitar amplifier.


T4C06

Which of the battery types listed below offers the longest life when used with a hand-held radio, assuming each battery is the same physical size?

A. Lead-acid B. AlkalineC. Nickel-cadmiumD. Lithium-ion


T4C06 Answer - D

Lithium-ion batteries have a high storage capacity for their size, so they last longer. They are generally more expensive. (You may already know that lithium-ion digital camera batteries last longer than any other kind. If you do, you also already know they are more expensive.)


T4C07

What is the nominal voltage per cell of a fully charged nickel-cadmium battery?

A. 1.0 volts

B. 1.2 volts

C. 1.5 volts

D. 2.2 volts


T4C07 Answer - B

Although nickel-cadmium batteries, more commonly known as nicads, have a lower voltage than a typical alkaline battery of the same type, the difference is not that great, and they are rechargeable many times. For that reason, most handheld radios use nicads as a power source.


T4C08

What battery type on this list is not designed to be re-charged?

A. Nickel-cadmium

B. Carbon-zinc

C. Lead-acid

D. Lithium-ion


T4C08 Answer - B

Carbon-zinc batteries are the least expensive batteries, and they are the most common. However, they are designed for only a single use, and generally cannot be recharged.


T4C09

What is required to keep rechargeable batteries in good condition and ready for emergencies?

A. They must be inspected for physical damage and replaced if necessary

B. They should be stored in a cool and dry location

C. They must be given a maintenance recharge at least every 6 months

D. All of these answers are correct


T4C09 Answer - D

Amateur operators are often called on to provide communications in an emergency. Many emergencies result in a loss of commercial power. If you want to help, you need to insure that your batteries are properly stored, charged and maintained so that you can be ready to deploy at a moment's notice.


T4C10

What is the best way to get the most amount of energy from a battery?

A. Draw current from the battery as rapidly as possible

B. Draw current from the battery at the slowest rate needed

C. Reverse the leads when the battery reaches the 1/2 charge level

D. Charge the battery as frequently as possible


T4C10 Answer - B

Drawing only the current you need will make the most of your battery's charge. Whatever you do, NEVER, NEVER, NEVER reverse the leads on a battery. This can seriously damage your equipment!


Group T4D

Group T4D covers the most important Ohm’s Law relationships .


Important (But Confusing) Abbreviations

We’re about to look at something called “Ohms law.” Ohms law is a very important mathematical formula that shows how voltage, current and resistance are related to each other. But before we can study the law, we need to look at the abbreviations for each of these values, and they are not what you would expect. They are:

Voltage – ECurrent – IResistance – R

You would expect that voltage should be abbreviated V and current should be C, but they are not. You’ll need to learn these three for what comes next.


Ohm’s Law

Ohms law ties voltage, current and resistance all together in one neat package. If you know any two of them, you can easily figure out the third. If you know a little algebra, you’ll only need to remember one formula. If you don’t, you’ll either need to remember three formulas or a little memory aide you’ll see in just a bit.


Ohms Law – Voltage UnknownRemember our little flashlight

circuit? Suppose you know the current and resistance in that circuit and you want to know the voltage. Use this formula:

Voltage (E) equals current (I) multiplied by resistance (R)

If you use the abbreviations, it is simply:

E = I x R

We’ll see how you actually use this in just a bit.


Ohms Law – Current Unknown

Using the same circuit, suppose you know the voltage and the resistance, but you don’t know the current. If so, the formula you use is:

Current (I) equals voltage (E) divided by resistance (R)

Using just the abbreviations, the formula is:

E I = ---

R

We’ll use this one shortly, too!


Ohms Law - Resistance Unknown

Finally, using the same flashlight circuit one more time, suppose you know the current and the voltage, but you need to know the resistance. If so, the formula is:

Resistance (R) equals voltage (E) divided by current (I)

Using just the abbreviations, the formula is:

E R = ---

I


A Simple Solution!If you know algebra, you can take E = I x R

and come up with the other two equations. But, if you don’t know algebra and you don’t want to remember three different equations, there is another solution - it’s the Ohm’s Law Circle!


Ohm’s Law Circle

The Ohm’s Law circle is really easy to use. Draw it out on a piece of paper and keep it handy.

To use the circle, you will cover the value you don’t know with your hand. If the two values you know are beside each other, you multiply them together. If one is over the other, divide the lower value into the upper value.

(Don’t panic! All will be explained…)


Ohm’s Law ProblemsWe promised all would be explained, so here

goes. Grab a piece of paper and let’s rumble!

OK, all these formulas and this circle might seem a little confusing, so let’s see how they work by going through a few problems. That should clear up any confusion you might have.

We’ll work each problem two ways. First, we’ll show you how to do it using the formula, and then we’ll work the same problem using the circle. It doesn’t matter which one you use to get the answer, so long as you can get the right answer.


Ohms Law Problem # 1 – Voltage Unknown

What is the voltage across the resistor if a current of 0.5 amperes flows through a 2 ohm resistor?

Solution:

E = I x RE = 0.5 x 2 = 1 volt

Or...



Using the circle, cover the E. You now have to multiply I times R to get the right answer of 1 volt.



What is the voltage across the resistor if a current of 1 ampere flows through a 10 ohm resistor?

Solution:

E = I x RE = 1 x 10 = 10 volts

Or, using the circle, cover the E. You now have to multiply I times R to get the right answer of 10 volts.



What is the voltage across the resistor if a current of 2 amperes flows through a 10 ohm resistor?

Solution:

E = I x RE = 2 x 10 = 20 volts

Or, using the circle, cover the E. You now have to multiply I times R to get the right answer of 20 volts.


Ohms Law Problem # 4 – Current Unknown

What is the current flow in a circuit with an applied voltage of 120 volts and a resistance of 80 ohms?

Solution: E

I = --- R

120I = --- = 1.5 amps

80

Or...



Using the circle, cover the I. You now have to divide E by R to get the right answer of 1.5 amps.



What is the current flowing through a 100 ohm resistor connected across 200 volts?

Solution: E

I = --- R

200I = --- = 2 amps

100

Or, using the circle, cover the I. You now have to divide E by R to get the right answer of 2 amps.




Solution: E

I = --- R

240 I = --- = 10 amps 24

or, using the circle, cover the I. You now have to divide E by R to get the right answer of 10 amps.


Ohms Law Problem # 7 – Resistance Unknown

What is the resistance of a circuit when a current of 3 amperes flows through a resistor connected to 90 volts?

Solution: E

R = --- I

90R = --- = 30 ohms

3

Or...



Using the circle, cover the R. You now have to divide E by I to get the right answer of 30 ohms.



What is the resistance in a circuit where the applied voltage is 12 volts and the current flow is 1.5 amperes?

Solution: E

R = --- I

12R = --- = 8 ohms

1.5

Or, using the circle, cover the R. You now have to divide E by I to get the right answer of 8 ohms.


Check-Up Time!




T4D01

What formula is used to calculate current in a circuit?

A. Current (I) equals voltage (E) multiplied by resistance (R)

B. Current (I) equals voltage (E) divided by resistance (R)

C. Current (I) equals voltage (E) added to resistance (R)

D. Current (I) equals voltage (E) minus resistance (R)


T4D01 Answer - B

There are three possible equations for Ohm's Law. There is also a great memory aid for those who don't like to remember equations. We’ll look at that later. First, here is the Ohm’s Law equation to find current (I):

EI = --- R


T4D02

What formula is used to calculate voltage in a circuit?

A. Voltage (E) equals current (I) multiplied by resistance (R)

B. Voltage (E) equals current (I) divided by resistance (R)

C. Voltage (E) equals current (I) added to resistance (R)

D. Voltage (E) equals current (I) minus resistance (R)


T4D02 Answer - A

Here is the Ohm’s Law equation for determining voltage:

E = I x R


T4D03

What formula is used to calculate resistance in a circuit?

A. Resistance (R) equals voltage (E) multiplied by current (I)

B. Resistance (R) equals voltage (E) divided by current (I)

C. Resistance (R) equals voltage (E) added to current (I)

D. Resistance (R) equals voltage (E) minus current (I)


T4D03 Answer - B

Here is the Ohm’s Law equation to solve for current:

E

R = ---

I


T4D04

What is the resistance of a circuit when a current of 3 amperes flows through a resistor connected to 90 volts?

A. 3 ohms B. 30 ohms C. 93 ohms D. 270 ohms


T4D04 Answer - B

You can solve this by using this formula:

ER = --- I

E 90R = --- = --- = 30 Ohms I 3


Or You Can Use the Ohm’s Law Circle


For Resistance...

Cover the R (resistance), and divide E (voltage) by I (current):


T4D05

What is the resistance in a circuit where the applied voltage is 12 volts and the current flow is 1.5 amperes?

A. 18 ohmsB. 0.125 ohms C. 8 ohmsD. 13.5 ohms


T4D05 Answer - C

You can solve this by using this formula:

ER = --- I

E 12R = --- = --- = 8 Ohms I 1.5


Or for Resistance...

Cover the R (resistance), and divide E (voltage) by I (current)


T4D06

What is the current flow in a circuit with an applied voltage of 120 volts and a resistance of 80 ohms?

A. 9600 amperesB. 200 amperesC. 0.667 amperesD. 1.5 amperes


T4D06 Answer - D

You can solve this one by using the formula:

EI = --- R

E 120I = --- = --- = 1.5 amperes R 80


Or for Current...

Cover the I (current), and divide E (voltage) by R (resistance)


T4D07

What is the voltage across the resistor if a current of 0.5 amperes flows through a 2 ohm resistor?

A. 1 voltB. 0.25 voltsC. 2.5 voltsD. 1.5 volts


T4D07 Answer - A


E = I x R

E = I x R = 0.5 x 2 = 1 volt


Or for Voltage...

Cover the E (voltage), and multiply I (current) times R (resistance)


T4D08

What is the voltage across the resistor if a current of 1 ampere flows through a 10 ohm resistor?

A. 10 voltsB. 1 voltC. 11 voltsD. 9 volts


T4D08 Answer - A


E = I x R

E = I x R = 1 x 10 = 10 volts


Or for Voltage...



T4D09

What is the voltage across the resistor if a current of 2 amperes flows through a 10 ohm resistor?

A. 20 voltsB. 0.2 voltsC. 12 voltsD. 8 volts


T4D09 Answer - A


E = I x R

E = I x R = 2 x 10 = 20


Or for Voltage...



T4D10


A. 20,000 amperes

B. 0.5 amperes

C. 2 amperes

D. 100 amperes


T4D10 Answer - C


EI = --- R

E 200I = --- = --- = 2 amperes R 100


Or for Current...



T4D11


A. 24,000 amperes

B. 0.1 amperes

C. 10 amperes

D. 216 amperes


T4D11 Answer - C


EI = --- R

E 240I = --- = --- = 10 amperes R 24


Or for Current...



Group T4E

Group T4E covers how to calculate power, as well as some of the

common units used in electronics - kilo, mega, milli, and micro.


“I’ve got the Power!”

Now that you have Ohms law all figured out, power should be really easy. First, you need to remember that the unit used to describe electrical power is the watt. When we measure the amount of electrical power used or produced, the watt is always our basic unit.


The Power FormulaThe formula used to calculate electrical

power in a DC circuit is:

Power (P) equals voltage (E) multiplied by current (I)

You already know the abbreviations for current and voltages, but now we add a new one – P for power. Using this abbreviation, you can rewrite the formula as:

P = E x I

But the old pros change the order of E and I around slightly so that the short formula becomes a real “pie” job:

P = I x E or P=IE (Get it?)


Power – Making Things Complicated!

OK, just like Ohms law, you have three different things to worry about – power, voltage, and current. If you know any two of them, you can figure out the third. Also like Ohms law, if you know algebra, you can take P = E x I (or P = I x E) and get formulas for figuring out either E or I.

And as with Ohms law, if you don’t know algebra, you’ll either have to memorize three equations or use the power circle. (Yes, Virginia, there IS a power circle!)


The Other Equations – Voltage Unknown

Suppose you know the power and the current, but you don’t know the voltage. In that case, the formula is:

PE = ---

I


The Other Equations – Current Unknown

Suppose you know the power and the voltage, but you don’t know the current. In that case, the formula is:

P

I = ---

E


The Power Circle

The power circle looks very similar to the Ohms law circle:


The Power CircleIt works the same way as well. Cover the value

you don’t know with your hand. If the two values you know are beside each other, multiply them together. If one is over the other, divide the lower value into the upper value.


Power Problems

Now let’s look at some power problems. We’ll look at two solutions – one with the formula, and one using the circle.


Power Problem # 1 – Power Unknown

How much power is represented by a voltage of 13.8 volts DC and a current of 10 amperes?

Solution:

P = E x I (Or you can use P = I x E)

P = 13.8 x 10 = 138 watts

Or...



Using the circle, when you cover P, you see that you have to multiply I times E to get the correct answer of 138 watts.



How much power is being used in a circuit when the voltage is 120 volts DC and the current is 2.5 amperes?

Solution:

P = E x I (Or you can use P = I x E)

P = 120 x 2.5 = 300 watts

Or, using the circle, when you cover P, you see that you have to multiply I times E to get the correct answer of 300 watts.


Power Problem # 3 – Current Unknown

How many amperes are flowing in a circuit when the applied voltage is 120 volts DC and the load is 1200 watts?

Here, we need one of the other formulas, and the solution is:

PI = ---

V

1200I = ---- = 10 amps

120

Or...


Power Problem # 3 – Current Unknown

Using the circle, when you cover I, you see that you have to divide P by E to get the correct answer of 10 amps.


Power Problem – Practical Application

How can you determine how many watts are being drawn by your transceiver when you are transmitting?

Solution:

If you need to know power, the formula you use is P = E x I (or P = I x E)

But in order to get the power, you need to know the voltage and current. To do that, you’ll have to measure them. You can measure the DC voltage at the transceiver using a voltmeter or multimeter. Then you need to measure the current drawn when you transmit using an ammeter or multimeter. Once you have those two values, you multiply voltage times the current


Important Unit PrefixesWe are almost done with the math for a bit,

but we still need to learn some important number prefixes. Sometimes, we have numbers that are really large or really small, and they become hard to work with. We have already seen two of them used in measuring radio frequencies – kilohertz and megahertz. Remember that one kilohertz (KHz) equals 1000 Hertz, and that one megahertz (MHz) equals one million Hertz. The prefix “kilo” means one thousand, and the prefix “mega” means one million.

Lets look at a few more...


Milli-

The prefix “milli-“ means one one-thousandth. We use it with units such as watts, amperes, and volts.

1 milliwatt = 1/1000 of a watt

1000 millwatts = 1 watt

1 milliampere = 1/1000 of an ampere

1000 milliamperes = 1 ampere


Example

With that in mind, how many milliamperes is the same as 1.5 amperes?

Solution:

Since there are 1000 milliamperes in 1 ampere, there are 1500 milliamperes in 1.5 amperes.


An Example using Milliwatts

How many watts does a hand-held transceiver put out if the output power is 500 milliwatts?

Solution:

Since there are 1000 milliwatts in 1 watt, 500 milliwatts would be half that, or .5 watts.


Micro-

“Micro-“ is another important prefix. It is also used with watts, amperes and volts as needed. Micro- means one one- millionth.

1 microvolt = 1/1,000,000 volt

1,000,000 microvolts = 1 volt


Example – Kilo-

What is another way to specify the frequency of a radio signal that is oscillating at 1,500,000 Hertz?

Solution:

Since 1 kilohertz (KHz) equals 1000 Hertz, if you divide 1,500,000 by 1000, you’ll get 1500 kilohertz (KHz)


Another Example – Kilo-

How many volts are equal to one kilovolt?

Since “kilo-“ means one thousand, there are one thousand volts in a kilovolt.

Whew!

Breathe a big sigh of relief. You have now done almost all the math you need for the Technician exam!


Check-Up Time!




T4E01

What unit is used to describe electrical power?

A. Ohm

B. Farad

C. Volt

D. Watt


T4E01 Answer - D

The basic unit of electrical power is the watt. Watts may measure power produced, such as the output of a transmitter, or power consumed, such as the power required by a 100 watt light bulb.


T4E02

What is the formula used to calculate electrical power in a DC circuit?

A. Power (P) equals voltage (E) multiplied by current (I)

B. Power (P) equals voltage (E) divided by current (I)

C. Power (P) equals voltage (E) minus current (I)

D. Power (P) equals voltage (E) plus current (I)


T4E02 Answer - A

The formula for power is:

P = I x E(watts) (amperes) (voltage)

But if you don’t like formulas, power calculations can also be done with a memory aid.


T4E03

How much power is represented by a voltage of 13.8 volts DC and a current of 10 amperes?

A. 138 watts

B. 0.7 watts

C. 23.8 watts

D. 3.8 watts


T4E03 Answer - A

Using the formula:

P = I x E

P = 10 x 13.8 = 138 watts

Or, if you prefer a memory aid, the memory aid for power looks similar to the one for Ohm’s Law and works exactly the same way...


Memory Aid for Power

To calculate a missing value, cover that value with your hand and multiply or divide the two remaining values as indicated.


For this Problem...

Cover the P (power) and multiply I (current) times E (voltage)


T4E04

How much power is being used in a circuit when the voltage is 120 volts DC and the current is 2.5 amperes?

A. 1440 wattsB. 300 wattsC. 48 wattsD. 30 watts


T4E04 Answer - B

To solve this problem:

P = I x E = 2.5 x 120 =

300 watts

Or, if you use the memory aid...


For this Problem...

Cover the P (power) and multiply I (current) times E (voltage)


T4E05

How can you determine how many watts are being drawn by your transceiver when you are transmitting?

A. Measure the DC voltage and divide it by 60 Hz

B. Check the fuse in the power leads to see what size it is

C. Look in the Radio Amateur's HandbookD. Measure the DC voltage at the transceiver and multiply by the current drawn when you transmit


T4E05 Answer - D

This is a practical application of P = I x E. First you measure the voltage going to the transmitter and the current drawn (or used) when the transmitting. Then, using the formula, you multiply current times voltage to get the number of watts drawn.


T4E06

How many amperes are flowing in a circuit when the applied voltage is 120 volts DC and the load is 1200 watts?

A. 20 amperesB. 10 amperesC. 120 amperes D. 5 amperes


T4E06 Answer - BIf you are a math whiz, you can figure this

one out by changing the formula around to:

PI = ---

E

1200I = ---- = 10 amperes 120

0r...


Use the Memory Aid

Cover the I (current) and divide P (power) by E (voltage)


T4E07

How many milliamperes is the same as 1.5 amperes?

A. 15 milliamperes

B. 150 milliamperes

C. 1500 milliamperes

D. 15000 milliamperes


T4E07 Answer - C

The prefix “milli” means 1/1000, so 1000 milliamperes equals one ampere. To find out how many there are in 1.5 amperes, you multiply 1.5 times 1000.

1.5 amperes x 1000 = 1500 milliamperes


T4E08

What is another way to specify the frequency of a radio signal that is oscillating at 1,500,000 Hertz?

A. 1500 kHzB. 1500 MHzC. 15 GHz D. 150 kHz


T4E08 Answer - A

One kiloHertz (kHz) equals 1000 Hertz. If you divide the frequency in Hertz by 1000, you’ll get the frequency in kHz:

1,500,000--------- = 1,500 kHz 1,000


T4E09

How many volts are equal to one kilovolt?

A. one one-thousandth of a volt

B. one hundred volts

C. one thousand volts

D. one million volts


T4E09 Answer - C

The prefix “kilo” means 1000, so there are 1000 volts in one kilovolt.


T4E10

How many volts are equal to one microvolt?

A. one one-millionth of a volt

B. one million volts

C. one thousand kilovolts

D. one one-thousandth of a volt


T4E10 Answer - A

The prefix “micro” means one-millionth, so 1 microvolt = 1 one-millionth of a volt.


T4E11

How many watts does a hand-held transceiver put out if the output power is 500 milliwatts?

A. 0.02 watts

B. 0.5 watts

C. 5 watts

D. 50 watts


T4E11 Answer - B

1000 milliwatts equals 1 watt, so 500 milliwatts equals ½ watt or .5 watts.


Four Down, Six to Go!

This concludes Study Guide # 4.

Once you are satisfied that you can answer 80% of the questions in this Sub-element, you

are ready to move on to Study Guide # 5.

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