WS Flow of Electricity 2014 (Sol)

Chung Cheng High School (Main) Sec 2 Physics 2014

Chapter 13: Electrical Systems Name: ( ) Class: 2 _______ Date:

13.1 Flow of Electricity

1. The rate of the flow of electrical charges is called the ______________________.

A electric currentB electric circuitC ampereD voltage ( A )

2. The instrument used to measure the size of an electric current is known as the ______________ .

A rheostatB thermostatC voltmeterD ammeter ( D )

3. The SI unit for potential difference is the __________________.

A voltB kilowattC wattD milliampere ( A )

4. In the circuit below, both bulbs are identical. Which of the following statements below is incorrect?

A If one bulb is removed, the voltmeter reading will change.B If one bulb is removed, the ammeter reading will change.C If one bulb is removed, the other bulb will still light up.D If one cell is removed, both bulbs will be dimmer. ( A )

1


5. Which one of the following statements is correct when connecting an ammeter in a closed circuit?

A The negative terminal of an ammeter is connected to the negative terminal of a battery, and the positive terminal of an ammeter is connected to the positive terminal of a battery.

B The negative terminal of an ammeter is connected to the positive terminal of a battery, and the positive terminal of an ammeter is connected to the negative terminal of a battery.

C The negative terminal of an ammeter is connected to the negative terminal of a battery, and the positive terminal of an ammeter is connected to the negative terminal of a battery.

D The positive terminal of an ammeter is connected to the positive terminal of a battery, and the negative terminal of an ammeter is connected to the positive terminal of a battery. ( A )

6. The potential difference (or p.d.) between two points is the amount of energy / work done needed

to move one unit of positive charge from one point to another.

7. The resistance of a component is the ratio of the potential difference across it to the current

flowing through it.

8. Redraw the following circuits by using the correct circuit symbols.

2


9. For the following circuit, a) Draw in the ammeter to measure the b) Draw in the ammeter to measure the

current flowing through resistor A. current flowing through resistor B.

c) Draw in the voltmeter to measure the d) Draw in the voltmeter to measure the voltage across resistor A. voltage across the cell.

3

V

A B A B

A

A

AV


10. Calculate the combined resistance of the following resistors arrangements

Review:

Resistance in series

4

Working

RT = 2.0 + 5.0 = 7.0 Ω

Working

RT =

= 1.4 Ω

Working

RT =

= 0.97 Ω

Rtotal = R1 + R2 + R3 + …

A B A B

V V


Resistance in parallel

11. The diagram shows a simple electrical circuit.

(a) Determine the current I1 in the circuit.

I1 =

= 3.0 A

(b) Determine the current I2 in the circuit.

I2 =

= 1.5 A

(c) What is the total current flowing in the circuit?

IT = 1.5 + 3.0 = 4.5 A

(d) What is the total resistance in the circuit?

RT =

= 1.33 Ω

12. State the relationship between resistance, voltage and current based on Ohm’s Law

Using the above relationship, complete the table shown below.

5

Rtotal =

V = IR


Current / A Voltage / V Resistance /

2.0 6.0 3.0

1.5 3.5 2.33

0.50 5.0 10

3.5 52.5 15

All values to 2 or 3 significant figures (no fraction / mix numbers allowed)13. Study the circuit below. If the ammeter has a reading of 2.0 A, a) What is the resistance of the resistor given that the e.m.f of the cell is 6.0 V?b) If the resistance is doubled, will you expect the ammeter’s reading to increase, decrease or stay

the same? Explain.

a) R = V/ I

=

= 3.0 Ω

b) I = V/R

If R is doubled, I will be half of its original amount. Hence, it will decrease.

14.

a) Find the e.m.f of the dry cell in the following circuit if the ammeter reads 1.0 A.

V emf = 1.0 x 2.0= 2.0 V

b) Find the current flowing across the 3.0 Ω resistor.

I1 =

= 0.67 A

c) Find the current produced by the dry cell.

IT = 0.67 + 1.0

6

A


= 1.67 A

d) If the 2.0 Ω resistor is now replaced with a 3.0 Ω resistor, without doing any calculation, will the current in part c) increase, decrease or stay the same? Explain

The current in part (c) will decrease. There is a higher resistance for current to pass through the 3.0 Ω, resulting in lesser total current.

7

WS Flow of Electricity 2014 (Sol)

Documents

Transcript of WS Flow of Electricity 2014 (Sol)