Servei Àgora circ… · Web viewIncandescent bulb 100W 220 100 P/V = 0,45 V/I = 485 P*t/1000 =...

Ernest FERRER ELECTRIC CIRCUITS Activities. Lesson 1

Lesson 1 Understanding electric magnitudes

Activity 1Watch the power point presentation about the hydraulic analogy of electricity. Now check the hydraulic analogy at your school. Voltage: look at the pressure indicator on the fire-prevention hose at different

floor levels of your school. Now build a sentence, choosing the suitable words.

The water pressure (voltage)increase as you go updecrease go downis the same whatever floor you are on

Because

upstairs the potential energy of wateris higheris lower

downstairs is the same

Resistance and Intensity: look at any water tap. Obviously, as it is closed no water can flow. Now open it slowly and observe that, as you open it more, water can flow.

Summarize your observations and its analogy with electric circuits by filling the blanks in the text below with suitable words from the word bank. Be careful because there are more words than blanks to fill. Some could be used more than once.The tap is an _________ for the water circuit as the electrical_________ is an obstruction for

an electrical _________.

If the _________ is closed (infinite obstruction) no _________ can flow. If the electrical

resistance is _________ (open circuit or we put insulating materials like_________, plastic,

rubber, etc.) no electricity can _________.

As we _________ slowly the _________ the obstruction _________ and the water begins to

flow. As we decrease the obstruction the flow____________. If we put less insulating materials

(water, graphite, rust iron, steel, aluminium, _________, etc.) we see that _________ the

obstruction decreases the _________ of the current increases.

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obstruction open tap resistance copper infinite cork water decreases increases intensity as pass circuit


Activity 2Watch, read, listen to and repeat the slides and questions in the following internet presentations about electric voltage or potential difference (dp) What happens if the electric voltage increases in a simple circuit?

http://www.bbc.co.uk/schools/scienceclips/ages/8_9/circuits_conductors_fs.shtmlCopy the question and correct answer or complete sentence from the quiz.

5)

6)

7)

8)

Now assemble a simple circuit with wires, switch and light bulb but use a variable power supply. What happens if we increase the voltage slowly from zero to the full voltage the bulb can tolerate?

Summarize your observations writing some sentences using the structures proposed below. The first sentence it is already done as example

Voltage zero ¼ ½ ¾ Full

The bulb

has a very bright light

has a normal light

doesn’t light at all

has a bright light

has a dimly light

is very hot is slightly hot is cold is hot is warm

1) When the voltage is zero, the bulb doesn’t light at all and it is cold

2) When the voltage is_________, the bulb_________________ and it is __________

3)

4)

5)

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http://www.bbc.co.uk/schools/scienceclips/ages/8_9/circuits_conductors_fs.shtml


Activity 3Watch, read, listen to and repeat the slides and questions in the following internet presentations about electric resistance. What happens if the electric resistance increases in a simple circuit?

http://www.bbc.co.uk/schools/scienceclips/ages/10_11/changing_circuits_fs.shtmlCopy the question and correct answer or complete sentence from the quiz

1)

2)

3)

4)

5)

6)

7)

8)

9)

10)

Now assemble a simple circuit with a battery, wires, switch and a light bulb. Now add another bulb between the last one and the power supply. Finally add a 3 rd lit bulb. What can you observe? Now remake the circuit adding a very long, long wire, adding more switches, etc.

Voltage one bulb two bulbs three bulbs Three bulbs, long wires and several switches

brightness picture

Resistance small

Summarize your observations writing some sentences using the structures proposed below. The first sentence it is already done as example.

The bulb/s

has/ havea dimly light

has/ have a bright light

doesn’t/ don’t light at all

has/ have a normal light

is/are warm is/are hot is/are very hot is/are cold

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http://www.bbc.co.uk/schools/scienceclips/ages/10_11/changing_circuits_fs.shtml


1) When the circuit has one bulb, the bulb has a bright light and is very hot.

2) When the circuit has _____ bulbs, the bulbs have a _______light and are ________

3)

4)

The resistance is

small/medium high/very high with

just one bulb two bulbsthree bulbs

The highest resistance

happens withjust one bulb two bulbsthree bulbs

and a long wirea short wire

The smallest resistance

1) The resistance is _________________________ with ________________________.



The highest resistance happens with ____________________ and______________________

The smallest resistance happens with ____________________ and______________________

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Lesson 2 Electric measurements

Activity 1You have to get into teams of two. Read the summarized transcription about how to use a multimetre while you. Then listen to the presentation on http://www.youtube.com/watch?v=KzjMIcER4EUAs a 1st member of your team explain the meaning of the words written

below. You can use the presentation transcription, a monolingual on-line dictionary. http://dictionary.cambridge.org/ or an on-line encyclopaedia http://en.wikipedia.org/ Measurement is ______________________________________________________________

Gauge is ____________________________________________________________________

Continuity is _________________________________________________________________

Resistor code is ______________________________________________________________

Probes are __________________________________________________________________

Range is ____________________________________________________________________

As a 2nd member of your team, answer the following questions? Remember to begin an answer using the question..What is a multimetre? A multimetre is…

How do you use it? I/We use it ___________________________________________________

How to measure continuity? We measure continuity __________________________________

How to measure voltage? _______________________________________________________

How to measure current? _______________________________________________________

Activity 2You have to get into teams of four/five. Each student in the group receives a slip of paper with part of the instructions about how to use a multimetre. There are some missing words on each slip that you have to fill in with the words from the word bank below.

First read your slip and try to fill in the gaps.

Now read your slip to your group and ask them to help you check/fill the gaps.

Then the group works out the correct order of the text.

Next listen to the proposed order of instructions other groups have and

agree/disagree/correct ‘til all the class agree on the order.

Finally each group writes a question about the text and asks/answers questions with other

groups.

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http://en.wikipedia.org/

http://dictionary.cambridge.org/

http://www.youtube.com/watch?v=KzjMIcER4EU


Activity 3You have to get into teams of two. First write down the multimetre parts on the picture.

Now draw two probes, one red and one black and set them to the jack/s that they can be connected to.

Finally compare this multimetre with the multimetre you have in your technology workshop. Explain the similarities and the differences you have found: number of jacks,Measurements able to do, screen pictures, etc.

Picture multimetre Technology workshop multimetre

Similarities

Differences

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Display, On/Off button or position, Voltmeter AC, Voltmeter DC Ohmmeter, Ammeter DC, Ammeter AC, Continuity, Common jack, Volt/Ohm jack, Amp jack, Selecting wheel, Other(diodes)


Activity 4Continuity test. No power supply is needed for continuity test, because the multimetre provides the required energy and also works as a buzzer.The continuity test checks if electricity can pass

through an electric component, this is if a connection between two points of the circuit exists.

Set the red probe to VΩ. Set the measuring wheel (knob) to Ohm, musical note. If necessary, press function button to make musical note appear on the metre screen.

Now experiment with the metre and choose/write the answera) Check if the continuity test works by linking the probes. ANSWER: If the metre beeps, it’s OK/it works/it is working/it is correct.

b) Check if a spare wire is OK. ANSWER: If the metre beeps/doesn’t beep, it’s OK/it works/it is working/it is correct.

c) Check if a wire within the circuit is OK. ANSWER:

d) Check if a switch in on position is OK. ANSWER:

d) Check if a switch in on position is OK. ANSWER:

Think what problem is happening when the multimetre beeps/doesn’t beep at the right position.

Activity 5Resistance measurement. No power supply is needed for this test, because Ohmmetre provides the required energy. The multimetre works as a Voltmetre and an

Ammetre together, using the Ohm’s law to calculate Resistance.The Ohmmetre measures the opposition that substances have against the flow of electricity. Instructions: Set the red probe to VΩ. Set the measuring wheel (knob) to Ohm. Choose the gauge according with the expected resistance value. Big resistance use M for MegaOhms (106

Ohms). Small resistances use Ohms.Sample Selected gauge Measure Insulator or Conductor?

Spare wire

Bulb 12 V

Bulb 230 V

A key

Dry finger

Wet finger

Dry wood

Wet wood

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Activity 6Voltmeter measurement. To measure voltage, circuit needs power supply. The Voltmetre has a big resistance.

It measures the potential difference between two points of the circuit, which means the energy that electrons loss when they pass through an electrical component. It is used to measure the voltage effect of each electric component.

Look at the following circuits diagrams used to measure voltage.

Voltmeter serial at the battery Voltmeter parallel at the bulb lit Voltmeter serial at the bulb light

Voltmeter parallel at the battery Voltmeter serial at the switch Voltmeter parallel at the switch

Which of them do you think are wrong / correct / useless? Justify your decision.Will the bulb light up or not, Will the main current will through the bulb circuit or the meter, Will the multimetre reading be high/normal/low, etc.

The first is already done:The top left diagram (Voltmeter series at the battery) is incorrect because in this disposition Voltmetre, as it has high resistance, prevents current from flowing through the bulb. The bulb will not light on, and the multimetre reading will be useless.

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Now, it’s your turn:The top middle diagram (Voltmeter parallel at the bulb) is______________________________

The top right diagram (Voltmeter serial at the bulb) is_________________________________

The bottom left diagram (Voltmeter parallel at the battery) is____________________________

The bottom middle diagram (Voltmeter series at the switch) is___________________________

The bottom right diagram (Voltmeter parallel at the switch) is___________________________

Now assemble the circuits respecting the voltage prescribed by your teacher and check if your predictions are true. Check for each assembly if the light bulb turns on and off. Use a Voltmetre to measure.

Instructions: Set the red probe to VΩ. Set the measuring wheel (knob) to DCV: Direct current voltage. Choose the gauge according with the expected voltage value.Write down your measurement inside each picture above.

Complete comparative sentences about the voltage values obtained in circuits where the bulb turns on. (the same, highest that, smaller than, slightly highest than)

The voltage measured at the battery is ________________ the voltage measured at the bulb.

The voltage measured at the bulb is __________________ the voltage measured at the switch.

The voltage measured at the switch is ________________ the voltage measured at the battery.

Finally write a summary about multimetre use and safety.For measuring the circuit/bulb/battery voltage... you must/mustn’t1)

2)

3)

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Activity 7Ammetre measurement. To measure intensity, circuit needs power supply. The Ammetre has a very small, nearly zero, resistance,

It measures the flow of current through a part of the circuit, which means how many electrons pass at a given time at a point. It is used to know the current passing through a section of the circuit.

Look at the following circuits diagrams used to measure intensity.

Ammeter serial at the battery Ammeter parallel at the bulb Ammeter serial at the bulb

Ammeter parallel at the battery Ammeter serial at the switch Ammeter parallel at the switch

Which of them do you think are wrong / correct / useless? Justify your decision.Will the bulb light up or not, Will the main current will through the bulb circuit or the meter, Will the multimetre reading be high/normal/low, etc.

The first is already done:The top left diagram (Ammetre serial at the battery) is correct because in this disposition Ammetre, as it has a very small resistance, allows current to flow through the bulb. The bulb will light on, and the multimetre reading will be normal, measuring current passing through the circuit.

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Now, it’s your turn:The top middle diagram (Ammetre parallel at the bulb) is_______________________________

___________________________________________________________________________

The top right diagram (Ammetre serial at the bulb) is_________________________________

___________________________________________________________________________

The bottom left diagram (Ammetre parallel at the battery) is____________________________

___________________________________________________________________________

The bottom middle diagram (Ammetre series at the switch) is___________________________

___________________________________________________________________________

The bottom right diagram (Ammetre parallel at the switch) is____________________________

___________________________________________________________________________

Now assemble the circuits respecting the voltage prescribed by your teacher and check if your predictions are true. Check if the lit bulb turns on and off. Use an Ammetre to measure.

Warning: Be very careful because some of the circuits are dangerous (shortcircuit) if connected over very low voltage. If possible use a power supply unit instead of a battery. Instructions: Set the red probe to A. Set the measuring wheel (knob) to DCA: Direct current Intensity. Choose the gauge according with the expected intensity value.Write down your measurement inside each picture above.

Why intensity measurements are always the same on circuits where the bulb turns on? ANSWER: ___________________________________________________________________

Finally write a summary about multimetre use and safety.For measuring the circuit/bulb/battery intensity... you must/mustn’t

1)

2)

3)

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Activity 8

Measurement Power on circuit? Circuit diagram with metre, series or parallel

How the meter works

Voltmeter

Ammeter

Continuity

Ohmmeter

Circuit power on

Circuit power off

Power off & isolated element

Big resistance

Small resistance

A battery and a buzzer

A battery with a Voltmetre and a Ammetre working together

Choose the explanation that fits better with each possible measurement the multimetre (meter) can do. Series: meter inside the only possible electricity path Parallel: meter in a different electricity path.

Now summarise information with a sentence for each measurement. The first is already done...

The Voltmetre works with circuit power on. The Voltmetre has a big resistance, so it must be

connected in parallel with the element we are going to measure.

The Ammetre works ___________________________________________________________

___________________________________________________________________________.

The Ohmmetre works __________________________________________________________

___________________________________________________________________________.

The Continuity test works _______________________________________________________

___________________________________________________________________________.

Activity 9Ohm’s law: assemble a simple circuit using a variable power supply station and a meter to measure both voltage and intensity. Do measurements and take records as the voltage slowly increases from zero to the full voltage tolerated by the bulb.

Power supply voltage Zero ¼ ( V) ½( V) ¾( V) full( V)

Voltmeter at the battery(V)Voltmeter at the bulb (V)

Ammeter (A)

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Measure the resistance of the bulb alone (0 voltage) with the Ohmmeter.Use the Ohm’s law Voltage (V) = Resistance (Ω) x Intensity (A) to calculate the resistance of the bulb and check if the Ohm’s law is fulfilledPower supply

voltage Zero ¼ ( V) ½( V) ¾( V) full( V)

Measured resistance Calculated resistance using Ohm’s law. R = V/I

Bulb’sresistance (Ω)

According with your observations, complete the sentences using increases /decreases /remains the same.If the Voltage increases the bulb’s resistance _________________.

If Intensity decreases, the bulb’s resistance __________________.

Activity 10Expand the table you did in the previous activity to fill in the information you can calculate about energy and power in your basic circuit. Remember the Power and Energy formulas you already know:

Electric Power (W) = Voltage (V) x Intensity (A)Energy consumed or Work (kW.h) = Electric Power (W) x time working (hours)

Power supply voltage Zero = 0 V ¼ =___ V ½ =___ V ¾ =___ V Full =___ V

Power (W)

Daily (24h) consume of Energy (Kw.h)

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Activity 11Electric appliances and light bulbs always give information about the voltage required to work properly and the power they provide at the given voltage. With the compulsory advice of your parents & teachers analyse at least 12 electric appliances and lights at home or at school and record the voltage and power

information. Most electrical appliances have the required information in a plate on its back or in the instructions leaflet.Now calculate the rest of electrical magnitudes for each one, including consumption if they are connected for a whole day: 24 hours.The first is done as an example. a 100 Watts bulb working at 220 Volts has a current of I(A)=P(W)/V(V)=100W/220V = 0,45A

The bulb resistance according to Ohm’s law is R (Ω) = V(V)/ I(A) = 220 V/ 0,45A = 485 Ω

The daily energy consumed is E (kW.h) = P (kW) x time (hours) = 100 W* 1Kw/1.000W *

24 h = 2,4 kW.h. Remember to convert W into kW by dividing by 1000!

Fill in the table with the information recorded and calculated. Suggestion: You can use a processing sheet (Excel) to calculate the results.

Electric components

Voltage use (V) Power provided

(W)

CalculatedIntensity

(A)

CalculatedResistance

(Ω)

Daily consume of

Energy (Kw.h)Incandescent bulb 100W 220 100 P/V = 0,45 V/I = 485 P*t/1000 = 2,4

Incandescent bulb 60 W 220

Incandescent bulb 40 WEnergy saving bulb 12W

Blender

Washing machine

Fridge

Television “Telly”

Computer

Other appliances: DC bulb, dish washer, hair dryer, clothes dryer, toaster, HI-FI, wide screen, console, printer, speakers, radio, microwave, oven, freezer, fan, electric radiator, heater, radio, air conditioned, etc.

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According with your observations complete the sentences using: increases, decreases, remains the same Resistance...For a given voltage, if Power increases, then Intensity...

Energy consume...

Energy consume...For a given voltage if Resistance increases, then Intensity...

Power...

Discuss results with your partner and justify your observations. You can use the Water circuit analogy to clarify your ideas.

Activity 12Take an old electricity bill from home. Cut out the information about your account and bank where the bill is charged. Now analyze the information provided on the bill.

a) You pay for the right to have electricity: the power payment. (‘Potència’) This is a fixed amount for each kW you can use, even if you are not using it because you are on holiday. The device that controls your power limit is called Main Switch or Main circuit breaker (ICP “Interruptor de Control de Potència”) If you overload your fitting, the ICP disconnects all your appliances and lights.

How many kW can you use at home? How much does it cost? Available power in kW at

home Daily kW cost Number of days Total cost in bill

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b) You pay for the electricity you use: the energy payment. (‘Consum’) This is a variable amount depending on how many kWh you really use. If you are on holiday, you don’t pay anything, except for the fridge...The device that controls your consume is called electric meter. (“comptador electric”) The more energy you consume, the highest measurement the meter will record and the more expensive your energy payment will be.

How much does it cost? Calculate the cost of each kW.hElectricity used in kW.h kW.h cost Total cost in bill

Now calculate the cost of some bulbs and electrical appliances at home if they are connected on all the day along.

Bulb orappliance

Incandescentbulb 60 W

Energy savingbulb 12W Computer Telly Fridge

Daily cost in €

Do you think it is worthwhile switching the bulbs and appliances off when you aren’t using them?

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Activity 13All the units we use to measure electricity and energy are called after the people who discovered and explained the electricity phenomenon or invented any electricity device.

Search them on the Internet.http://en.wikipedia.org/wiki/International_System_of_Units

Look also for important people who do not have a unit named after them: Benjamin Franklin, Thomas Alva Edison, Luigi Galvani, etc. What is the character you like the most? Why?

Now choose two of them and search for biography information on the Wikipedia or other Internet sites. http://www.energyquest.ca.gov/scientists/index.htmlHere you have an example with questions you can answer for each one...

What is his/her forename and surname? What was his/her nationality? Georg Simon OHM. German

When and where did he/she live?1789-1854. Bavaria, Germany.

What was he/she studying at the time of his/her achievement?He was working as a Mathematics teacher in The Jesuit Gymnasium of Cologne where he was experimenting on physics in the physics laboratory.

What did he/she discovered, explained or invented? He discovered the Ohm’s law. Ohm's law states that the current through a conductor between two points is directly proportional to the potential difference (i.e. voltage drop or voltage) across the two points, and inversely proportional to the resistance between them. The mathematical equation that describes this relationship is I = V/R where I is the current, V is the potential difference in volts, and R is a circuit parameter called the resistance (measured in ohms, also equivalent to volts per ampere)

Was his/her achievement useful at his/her time?His work greatly influenced the theory and applications of current electricity at that moment.

Did he/she get any recognition for his/her achievement?At first Ohm's work was received with little enthusiasm. However, his work was eventually recognized by the Royal Society with its award of the Copley Medal in 1841. He became a foreign member of the Royal Society in 1842, and in 1845 he became a full member of the Bavarian Academy of Sciences and Humanities.

Was he/she in contact, sharing or arguing with other electricity researchers at his/her time? Which ones and about what?He drew considerable inspiration from Fourier's work on heat conduction in the theoretical explanation of his work.

You can also write a 4-5 sentences summary with all the information about your character or complete a table like this:

Character and

profession

When and where did he live?

He is Famous for... Prizes, titles, memberships,...

Georg Simon OHM. Teacher

1789-1854. Bavaria, Germany.

He discovered the Ohm’s law: the current through a conductor is directly proportional to the voltage, and inversely proportional to the resistance. I =V/R

Member of Bavarian Academy. Royal Society member and medal.

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http://www.energyquest.ca.gov/scientists/index.html

http://en.wikipedia.org/wiki/International_System_of_Units


Lesson 3 Series and parallel circuits

Activity 1Read the following diagram about a series resistor circuit. Think about what will happen with voltage, intensity and resistance when we increase the number of bulbs in series.

Write 4 sentences with your predictions: increases↑/decreases↓/remains the same =In a series circuit, as the number of bulbs increase, I think...The circuit voltage___________________________

The circuit intensity__________________________

The circuit resistance_________________________

The bulbs light... goes dimmer / stays the same / goes brighter

Now assemble the circuit using only a bulb, then two and finally three bulbs with the same power in series.

Use a multimetre to measure the voltage and current of the circuit. Calculate the circuit resistance also.

Record the measurements in a table:

Seriesbulbs zero one two three

Measured Voltage at one bulb V1

Measured Voltage at the battery VT

Measured Intensity at any point I1, IT

Calculated Resistance of one bulb R1

Calculated Resistance of the circuit RT

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Correct your predictions according to your observations and measurements.What will happen to the circuit if one bulb goes out? Check it.

Now read the series circuit laws and check if your circuit follows them by replacing the measurements in the equations.

We use the same type of bulb so all have the same Resistance R = R1 = R2 = R3

VT = V1 + V2 + V3 IT = I1 = I2 = I3 RT = R1 + R2 + R3= 3R

Remember that Ohm’s law always works either with one bulb or the entire circuit. Replace the measurement in the equationsVT = RT x IT V1 = R1 x I1 V2 = R2 x I2 V3 = R3 x I3

ReportingWrite a report of the serial circuit using the model provided by your teacher. Remember to attach some photos and diagrams. Use your corrected predictions as conclusions.

Activity 2Read the following diagram about a parallel resistor circuit. Think about what will happen with voltage, intensity and resistance when we increase the number of bulbs.

Write 4 sentences with your predictions: increases↑/decreases↓/remains the same =In a parallel circuit, as the number of bulbs increase, I think...The circuit voltage___________________________

The circuit intensity__________________________

The circuit resistance_________________________

The bulbs light... goes dimmer / stays the same / goes brighter

Now assemble the circuit using only a bulb, then two and finally three bulbs with the same power in parallel.

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Use a multimetre to measure the voltage and current of the circuit. Calculate the circuit resistance also.

Record the measurements in a table:

Parallelbulbs zero one two three

Measured Voltage at one bulb V1

Measured Voltage at the battery VT

Measured Intensityat one bulb I1

Measured Intensityat the battery IT

Calculated Resistance of one bulb R1

Calculated Resistance of the circuit RT

Correct your predictions according to your observations and measurements.What will happen to the circuit if one bulb goes out? Check it.

Now read the parallel circuit laws and check if your circuit follows them by replace the measurements in the equations

We use the same type of bulb so all have the same Resistance R = R1 = R2 = R3

VT = V1 = V2 = V3 IT = I1 + I2 + I3

1/RT = 1/R1 + 1/R2 + 1/R3 RT = R/3

Remember that Ohm’s law always works either with one bulb or the entire circuit. Replace the measurement in the equationsVT = RT x IT V1 = R1 x I1 V2 = R2 x I2 V3 = R3 x I3

ReportingWrite a report of the serial circuit using the model provided by your teacher. Remember to attach some photos and diagrams. Use your corrected predictions as conclusions.

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Activity 3Compare the series and the parallel resistor circuit you have just seen. Think about advantages and disadvantages of each one according to the length and quantity of wires required, the consequences of a bulb going out, the easiness to locate breakdowns, the consequences of using different power bulbs, etc.

Issue Serial circuit Parallel circuit

Number of wires required (more /less)

If a bulb goes out, the circuit...(still works / doesn’t work)

To locate breakdowns is... (easy /difficult)

When we add more resistors the total circuit Voltage... ↑↓ =When we add more resistors the total circuit Intensity ... ↑↓ =When we add more resistors the total circuit Resistance... ↑↓ =When we add more resistors the total circuit Power... ↑↓ =

If we use different power bulbs...

Other observations

Check your records with other students. Discuss and reach an agreement. Now use your statements to think what is the best circuit for using in industrial and/or residential electric installations? Justify your answer.

Now look for a real example of a series circuit and a parallel circuit

An example of a serial circuit is…

An example of a parallel circuit is…

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Activity 4a) Read carefully the following

circuit diagram and assemble it.

b) Write down the name of each electric component beside its number

c)Turn the switches on and off and write down what you observe for each of the four possible switch combinations. What bulbs light on?.Have they a bright or dim light? Is this a simple /series /parallel or mixed circuit?Redraw the simplified diagram of the lighted bulbs

Switch 2 up3 off

2 down3 off

2 down3 on

2 up3 on

Bulbs on, brightness

Circuit type

Equivalent simplifieddiagram

.d) Now think what happens in each combination. With the switch 2 up / down and switch 3 off/on, the resulting circuit is simple/series/parallel/mixed, so...

The bulb

number 4

...

is cold / warm / hot / very hot

number 5has a dim / normal / bright light/doesn’t light up at all

number 6

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Here you have an example1) With 2-way switch up and simple switch off, the resulting circuit is simple. The bulb 5 is very hot and has a bright light.

2) With

3) With

4) With

e) Now use a multimetre to measure the voltage and current of the circuit. Calculate the circuit resistance and power. Record the measurements in a table. Repeat the measurement for each possible combination of switches.

2-way up,Simple off

2-way downSimple off

2-way downSimple on

2-way upSimple on

Measured Voltage Vt provided by the BatteryMeasured Intensity Itthrough the BatteryCalculated Circuit Resistance Rt

Calculated Circuit Power

The most powerful circuit is_____________________________________

The highest resistance circuit is__________________________________

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Activity 5 Revise the slides and questions in the following internet presentations about serial batteries. What happens if we connect several batteries in series? http://www.bbc.co.uk/schools/scienceclips/ages/8_9/circuits_conductors_fs.shtml

Assemble a simple circuit with wires, a switch, a light bulb and a battery. Make sure you use a battery with a voltage about half of the required voltage of the bulb. Use a multimetre to measure the voltage and current of the circuit. Calculate the resistance of the light. Now increase the number of batteries, up

to three, placing them in series (one battery after the other following the same wire path) Record the new measurements in a table:

Seriesbatteries zero 1 2 3

MeasuredVoltage at bulb

MeasuredVoltage at one battery

MeasuredIntensity

CalculatedResistance of bulb

Summarise your observations As we increase the number of series batteries...The voltage....The intensity...The resistance...Series batteries are used for.....

Draw the serial batteries circuit diagram, including how you place the multimetre to measure.

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http://www.bbc.co.uk/schools/scienceclips/ages/8_9/circuits_conductors_fs.shtml


Now assemble a simple circuit with wires, a switch, a light bulb and a battery. Use a multimetre to measure the voltage and current of the circuit. Calculate the resistance of the light. Now increase the number of batteries, up to three, placing them in parallel: each battery has its own different wire path (all paths link to the bulb and to the switch) Record the new measurements in a table:

Parallelbatteries zero 1 2 3

MeasuredVoltage at bulb

MeasuredVoltage at one battery

MeasuredIntensity at one battery

MeasuredIntensity at bulb

CalculatedResistance of bulb

Summarise your observations.As we increase the number of parallel batteries...The voltage....The intensity...The resistance...Parallel batteries are used for.....

Draw the parallel batteries circuit diagram, including how you place the multimetre to measure.

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Lesson 4 Revision on electricity

Activity 1Watch and read the following cartoon link about what life in a Victorian House by the end of XIX century was like. Look how they washed clothes, heated and lit the house.

http://www.bbc.co.uk/education/dynamo/history/stepback.htmComplete the information searching on the Internet. Describe the following pre-electrical light devices: bonfire, hearth, torch, candle, oil lamp, paraffin lamp, gas lighting.

What kind of combustible did they use? How much light did they produce? How safe was the device? How easy to manage was the device? How much did the combustible cost?

Order all of them including the electrical bulb pointing at their advantages and inconveniences.

Device Century Advantages Disadvantages Still in use? Where and when

bonfire

hearth

torch

candle

oil lamp

paraffin lamp

gas lighting

light bulb

Search for photos or pictures of the different lighting techniques in order to illustrate and complete your table.

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http://www.bbc.co.uk/education/dynamo/history/stepback.htm


Activity 2Electricity word search. Find the following words in the puzzle:

Activity 3Memory game. Electric components: name, symbol and use.Play the game in groups of 2-4 students. Mix all the cards. Then display them all face down in rows and columns. The first player chooses a card and turns it over and reads/shows the card. Then he does a second and a third card

choice and also turns them over. If the three cards match, the player keeps them with him and scores 1 point. If they don’t match, he arranges them face down to their former places. Now it’s the second player’s turn. Once all the cards have been paired up, the player with more points wins. Below you have a sample of three cards that match.

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ammeter battery bulb cell current electricity lamp motor ohmmeter resistor switch voltmeter wire


Lamp (bulb)A transducer which converts electrical energy to light.

Activity 4Look for electric appliances around you at school and at home. Write their name and link them with the sort of energy they produce. Some appliances convert electricity to more than one energy type.

Electrical appliances Energy conversion Bulb

Light

Sound

Heat waste

Movement

Heat use

Noise

Activity 5Connect to the following links to play quiz games about energy and electricity. A quiz is a contest between two teams where you have to answer questions beginning with a given letter. You will see the instructions displayed on the internet site.

http://www.teachers-direct.co.uk/resources/quiz-busters/quiz-busters-game.aspx?game_id=294





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Activity 6Analyse the following circuits, where the bulbs are the same and the cells are the same.

Which bulb will be the dimmest? Which circuit will have the biggest current?

Write down the voltmeter reading in order, from highest to lowest.

Now analyse these four new circuits and answer..In which circuit will the ammeter show the lowest reading?In which circuit will the bulb(s) be brightest?In which circuit will the ammeter readings be highest?Write down the ammeter readings in order, from highest to lowest.

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Activity 7Complete the following electricity family tree. Ask your teacher or use a bilingual dictionary if you don’t understand a word.

Electricity

is a kind of ______

flows through a _____ with

Converted from

Primary

like______

renewable energies like

in Power Plants

water dams

switches like

electric converter

like

NC switch

motor

measured magnitudes like

Voltage Intensity

Ohmeter

through a device called ___________ with different meters

all three magnitudes related by _____ law

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Servei Àgora circ… · Web viewIncandescent bulb 100W 220 100 P/V = 0,45 V/I = 485 P*t/1000 =...

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