Department of Physics

Academic Year--2020-21

Grade: 10

Activity Sheet -2

Electric Circuits

Name: …………………………………

Section: ……………………………….
 Multiple Choice Questions

0625/11/M/J/16
1. What is the function of a relay?
A to allow a current in one circuit to operate a switch in another circuit
B to prevent an electric shock by earthing a metal case
C to protect a circuit by melting if the current becomes too large
D to transform a d.c. voltage to a different value

0625/11/M/J/16
2. The diagram shows part of a circuit used to switch street lamps on and off automatically.

In the evening it gets dark.

Which row shows the effect on the resistance of the light-dependent resistor (LDR) and on
the potential difference (p.d.) across it?
0625/21/M/J/16
3. The four circuits shown all include an a.c. power supply, two diodes and a lamp.
In which circuit is there a rectified current in the lamp?

0625/21/M/J/16
4. The diagram shows a combination of logic gates.

Input P is at a logic state 0 (low) and input Q is at a logic state 1 (high).

What are the logic states at output X and at output Y?
0625/23/M/J/16
5. The diagram shows a battery connected to two resistors.

Four students separately measure the electromotive force (e.m.f.) of the battery, the current
in the resistors, and the potential difference (p.d.) across resistor R.
Their results are shown in the table below.
Which row shows values with their correct units?

0625/22/F/M/16
6. Four lamps are each labelled 240 V.
In which circuit do all four lamps have normal brightness?
0625/22/F/M/16
7. The diagram shows a potential divider connected to two voltmeters P and Q.

The resistance of the variable resistor is decreased.

Which row shows what happens to the reading on each voltmeter?

0625/01/S/04
8. An electrical component is to be placed in the circuit at Z, to allow the brightness of the
lamp to be varied from bright to dim.

What should be connected at Z?

0625/21/O/N/16
9. The diagram shows a lamp in a circuit.

Which change to the circuit would increase the current in the lamp?
A adding another resistor in parallel with the one in the circuit
B adding another resistor in series with the one in the circuit
C decreasing the electromotive force (e.m.f.) of the battery in the circuit
D moving the lamp to point P in the circuit

0625/22/O/N/16
10. Two NAND gates are connected together as shown.
The arrangement acts like a single logic gate.
What is the name of this single logic gate?
A AND B NOR C NOT D OR
 Structured Questions

0625/M/J/41/16
1. Fig. 1.1 shows a 12V battery connected in a circuit containing resistors A, B, C and D.
Each resistor has a resistance of 6.0Ω.

Fig.1.1
(a) Calculate the combined resistance of
(i) resistors A and B,

12
Ω
resistance = ................................................................. [1]
(ii) resistors A, B and C,

(12×6)/(12+6)
4Ω

resistance = ................................................................. [2]

(iii) resistors A, B, C and D.
 4 + 6 = 10
Ω
resistance = ................................................................. [1]

(b) Calculate
(i) the current in the battery,

I = 12/10 = 1.2A
current = ................................................................. [1]
(ii) the energy transferred from the battery to the circuit in 50 s.

1.2×12×50

energy transferred = ................................................................. [2]

[Total: 7]

0625/M/J/41/16
2. (a) (i) Fig. 2.1 shows the symbol for a circuit component.

Fig. 2.1
Name this component.
............................................................................................................................................. [1]
(ii) In the space below, draw the symbol for a NOT gate.
 [1]

(b) Fig. 2.2 shows a digital circuit.

Fig. 2.2
Complete the truth table for this circuit.

[3]
(c) Suggest a modification to the circuit in Fig. 2.2 to produce the output Z in the truth table
below.
It may help you to compare this truth table with the truth table in (b).

...............................................................................................................................................................
.......................................................................................................................................................... [1]

[Total: 6]

0625/41/M/J/17
3. (a) The resistance of a circuit component varies with the brightness of the light falling on
its surface.
(i) State the name of the component.
............................................................................................................................................. [1]
(ii) Draw the circuit symbol for this component.

[1]

(b) Fig. 3.1 shows a 6.0 V battery connected in series with a 1.2 kΩ resistor and a thermistor.

Fig. 3.1
(i) At a certain temperature, the resistance of the thermistor is 2.4 kΩ.
Calculate the reading on the voltmeter.

voltmeter reading = ...........................................................[4]

(ii) The battery connected to the circuit in Fig. 3.1 is not changed.
Suggest a change that would cause the reading of the voltmeter to decrease.
............................................................................................................................................. [1]
[Total: 7]

0625/42/M/J/17
4. Fig. 4.1 shows a 12.0 V power supply connected in a circuit.

Fig. 4.1 (not to scale)

The circuit includes a lamp and a resistance wire AB of constant cross-sectional area. There
is a sliding contact that can be moved between A and B.

(a) The rating of the lamp at normal brightness is 6.0 V, 9.0 W.

Calculate
(i) the current in the lamp at normal brightness,

current = ...........................................................[2]
(ii) the resistance of the lamp at normal brightness.

resistance = ...........................................................[2]
(b) AB is 1.00 m long and has a resistance of 5.0 Ω. The lamp has normal brightness when
the sliding contact is at X.
(i) The sliding contact is moved to B.
Explain, without a calculation, why the lamp becomes dimmer.

...............................................................................................................................................

...............................................................................................................................................

.......................................................................................................................................... [1]

(ii) Calculate the distance AX for the lamp to have normal brightness.

distance AX = ...........................................................[3]
[Total: 8]

0625/03/S/07
5. Fig.5.1 shows part of a low-voltage lighting circuit containing five identical lamps.
 Fig.5.1

(a) Complete the circuit, by the addition of components as necessary, so that

(i) the total current from the supply can be measured,
(ii) the brightness of lamp E only can be varied,
(iii) lamps C and D may be switched on and off together whilst lamps A, B and E remain on.
[4]
(b) All five lamps are marked 12 V, 36 W. Assume that the resistance of each lamp is the
same fixed value regardless of how it is connected in the circuit.
Calculate
(i) the current in one lamp when operating at normal brightness,

current = ................................................ [1]

(ii) the resistance of one lamp when operating at normal brightness,

 resistance = ................................................ [1]
(iii) the combined resistance of two lamps connected in parallel with the 12 V supply,

resistance = ................................................ [1]

(iv) the energy used by one lamp in 30 s when operating at normal brightness.

energy = ................................................ [1]

(c) The whole circuit is switched on. Explain why the brightness of lamps A and B is much

less than that of one lamp operating at normal brightness.

...............................................................................................................................................

…...........................................................................................................................................

…….................................................................................................................................. [2]

[Total: 10]

0625/42/O/N/17
6. (a) Fig. 6.1 is a circuit diagram.
 Fig. 6.1
(i) State the names of circuit components A, B and C.
component A ........................................................................................................................
component B ........................................................................................................................
component C ........................................................................................................................
[2]
(ii) The circuit can be used to indicate a change in temperature.
State and explain what would be observed when the temperature changes from hot to cold.
..................................................................................................................................................

..................................................................................................................................................

..................................................................................................................................................

..................................................................................................................................................

..................................................................................................................................................

............................................................................................................................................. [4]

(b) Fig. 6.2 shows a digital circuit.

 Fig. 6.2
Complete column X of the truth table for this circuit. Use the blank column for your working.

[3]
[Total: 9]

0625/31/W/09
7. Fig.7.1 is a schematic diagram of an electronic circuit controlling a lamp.

Fig.7.1

(a) State the names of the logic gates A and B.

A.........................................................

B …....................................................

[2]

(b) The output of the temperature sensor is high (logic 1) when it detects raised temperature.
The output of the light sensor is high (logic 1) when it detects raised light levels.
State the outputs of A and B when the surroundings are

(i) dark and cold,

output of A = ..........................................

output of B = ..................................... [1]

(ii) dark and warm,

output of A = ..........................................

output of B = ..................................... [1]

(iii) bright and warm.

 output of A = .........................................

output of B = .................................... [1]

(c) (i) Suggest why B is connected to a relay, rather than directly to the lamp.

.......................................................................................................................................... [1]

(ii) The relay switches on when its input is high. In which of the three combinations in
(b) will the lamp light up?

.......................................................................................................................................... [1]

(iii) Suggest a practical use for this circuit.

.......................................................................................................................................... [1]

[Total: 8]
 End of Chapter Questions
Text Book questions

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What do you need to know?
The table below lists the things that you may be tested on in the examination.

Chapter 3 – Electrical Circuits

Topic Learning outcomes

understandi

understand
Need to do

Need some
help of the
ng of the

the topic
practice

Did not
teacher
Decent
Candidates should be able to:

more
topic
4.3.1 Circuit Draw and interpret circuit diagrams containing
diagrams sources, switches, resistors (fixed and
variable),
heaters, thermistors, light-dependent
resistors, lamps, ammeters, voltmeters,
galvanometers, magnetising coils,
transformers, bells, fuses and relays
Draw and interpret circuit diagrams containing
diodes
4.3.2 Series and Understand that the current at every point in a
parallel circuits series circuit is the same
Give the combined resistance of two or more
resistors in series
State that, for a parallel circuit, the current
from the source is larger than the current in
each branch
State that the combined resistance of two
resistors in parallel is less than that of either
resistor by itself
State the advantages of connecting lamps in
parallel in a lighting circuit
Calculate the combined e.m.f. of several
sources in series
Recall and use the fact that the sum of the p.d.s
across the components in a series circuit is
equal to the total p.d. across the supply
Recall and use the fact that the current from
the source is the sum of the currents in the
separate branches of a parallel circuit
Calculate the effective resistance of two
resistors in parallel
4.3.3 Action and Describe the action of a variable potential
use of circuit divider (potentiometer)
components Describe the action of thermistors and light
dependent resistors and show understanding
of their use as input transducers
Describe the action of a relay and show
understanding of its use in switching circuits
Describe the action of a diode and show
understanding of its use as a rectifier
Recognise and show understanding of circuits
operating as light-sensitive switches and
temperature-operated alarms (to include the
use of a relay)
4.4 Digital Explain and use the terms analogue and digital
electronics in terms of continuous variation and high/low
states
Describe the action of NOT, AND, OR, NAND
and NOR gates
Recall and use the symbols for logic gates

Design and understand simple digital circuits

combining several logic gates
Use truth tables to describe the action of
individual gates and simple combinations of
gates
 Think and reflect!
Chapter 3 – Electrical Circuits
Reflect your level of understanding by choosing a suitable number of learning scale. .

Learning
Self-reflection
scale

4 I know everything that was taught so well I can teach it to others.

3 I know and can do everything that was taught without mistakes.

I can do most of the things that were taught but need help with the
2
harder parts.

1 With help I can do some of what was taught.

0 I don’t know what was taught and can’t do any of it.

General reflection:

➢ What do you want to know more about this chapter?

➢ Mention best area of understanding and any area of difficulty, if you have.

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Teacher’s remarks:

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Teacher’s name / Signature

Date