CIE iGCSE Co-Ordinated Science P4.3.1 Circuit diagrams and circuit components Exam Style Questions Paper 3
Question
(a) A torch (flashlight) contains two cells, a lamp and a switch connected in series.
Fig. 3.1 shows an incomplete circuit diagram for the torch.
(i) Complete the circuit diagram in Fig. 3.1 for the torch using electrical symbols.
Fig. 3.1
(ii) A voltmeter is connected to measure the potential difference across the lamp.
Add a voltmeter to your circuit diagram in Fig. 3.1 using the correct electrical symbol.
(iii) Fig. 3.2 shows a cell and lamp used in the torch.
Use information from Fig. 3.2 to explain why two cells are used to light the lamp.
(iv) Use information from Fig. 3.2 to calculate the resistance of the lamp when lit.
(v) The cell provides an electromotive force (e.m.f.) to the circuit.
Complete the sentence.
The e.m.f. of an electrical source of energy is measured in ……………. .
(b) Fig. 3.3 shows a single ray of light from the torch shining on a mirror.
(i) State the relationship between angle K and angle L.
(ii) State the name of the dotted line AB.
(iii) State what happens to the ray of light at point C.
▶️Answer/Explanation
Ans : 3(a)(i) correct symbols for lamp and switch ;
all in series and all else correct ;
3(a)(ii) voltmeter connected across the lamp ;
correct symbol ;
3(a)(iii) lamp needs 3.0 V so two 1.5 V cells ;
3(a)(iv) resistance = pd/current (in any form) or 3.0 / 1.5 ;
= 2.0 (Ω) ;
3(a)(v) volts ;
3(b)(i) angle K equals angle L ;
3(b)(ii) normal ;
3(b)(iii) reflected / reflection ;
Question
Fig. 9.1 shows a washing machine.
(a) (i) The washing machine uses:
• a heater to heat the water
• a motor to pump the hot water through the machine.
The motor and the heater are connected in a parallel circuit.
The motor and the heater are each operated by separate switches.
The circuit symbol for a heater is 
The circuit symbol for a motor is 
Fig. 9.2 shows an incomplete circuit diagram for the washing machine.
Complete the circuit diagram on Fig. 9.2.
(ii) The resistance of the heater is 20 Ω.
The resistance of the motor is 80 Ω.
Identify from the list the most likely value for the combined resistance of the heater and
motor connected in parallel.
Explain your answer.
16 Ω 20 Ω 50 Ω 80 Ω 100 Ω
combined resistance = …………………………. Ω
explanation …………………………………………………………………………………………………………
(iii) The current in the wires of the electrical circuit is a flow of charged particles.
State the name of the particles that flow in the wires of the electrical circuit.
(iv) The current-carrying coil in the motor experiences a turning effect.
This turning effect can be increased by increasing the number of turns on the coil.
State two other ways to increase this turning effect.
1 …………………………………………………………………………
2 …………………………………………………………………………
(b) Inside the washing machine, some of the water evaporates.
During evaporation, water changes state from a liquid to a gas.
(i) Complete the diagrams in Fig. 9.3 to show the arrangement and separation of molecules
in a liquid and in a gas.
(ii) During evaporation, the water does not boil.
State the boiling point of water.
…………………………………………….. °C
▶️Answer/Explanation
Ans : 9(a)(i) all symbols correct ;
heater and motor in parallel connection ;
switches correctly placed ;
9(a)(ii) 16 (Ω) ;
combined resistance in parallel is less than either individual resistance ;
9(a)(iii) electrons ;
9(a)(iv) increase current ;
increase strength of magnetic field ;
9(b)(i) liquid – all molecules touching random arrangement ;
gas – molecules widely separated (no more than seven shown) and random arrangement ;
9(b)(ii) 100 (°C) ;
Question
A room in a house has an electric heater.
(a) Fig. 12.1 shows part of the circuit containing the heater.
Complete the circuit diagram in Fig. 12.1 by adding the correct electrical symbol for a fuse.
(b) When the circuit is switched on, the current in the heater is 3A and the supply voltage is 240V.
(i) Calculate the resistance of the heater.
State the unit of your answer.
resistance = ……………………………….. unit ………..
(ii) The fuse in the circuit needs to be replaced.
Explain why a 5A fuse is used and not a 3A fuse.
(c) Fig. 12.2 shows the heater as part of an underfloor heating system.
(i) When the heater is switched on, thermal energy passes through the solid floor to heat the air in the room.
The temperature of the air in the room increases slowly.
State the method of thermal energy transfer through the solid floor.
(ii) State the method of thermal energy transfer that heats all the air in the room.
(d) Some water spills onto the floor and evaporates.
Describe evaporation in terms of the motion of water molecules.
(e) There are solar cells on the roof of the house.
State one advantage and one disadvantage of generating electricity using solar cells. Do not include the cost.
advantage ………………………………………………………………………
disadvantage ………………………………………………………………….
▶️Answer/Explanation
Ans : 12(a) fuse inserted in gap using the correct symbol ;
12(b)(i) evidence of resistance = voltage / current (in any form) or 240 / 3 ;
= 80 ;
Ω / ohms ;
12(b)(ii) fuse needs to be slightly greater than maximum current (or it would blow in normal use) ;
12(c)(i) conduction ;
12(c)(ii) convection ;
12(d) faster moving / most energetic molecules (leave) ;
(leave) from the surface of the liquid ;
12(e) renewable energy / does not produce CO2 etc ;
need sunlight / only works during the day etc ;
Question
(a) An electric heater is used to heat a classroom in a school.
The arrows on Fig. 12.1 show the circulation of air around the classroom.
P and Q are two positions within the air circulation.
Complete the sentences using words from the list.
conduction convection cooled radiation warmed
Position P shows ………………………………. air.
Position Q shows ………………………………. air.
This method of thermal energy transfer is called ………………………………. .
(b) In the classroom, a student draws diagrams to represent the three states of matter.
Fig. 12.2 shows the diagrams drawn. Box X shows the arrangement of particles in a solid.
Box Y shows the arrangement of particles in a liquid.
(i) In box Z, draw the arrangement of particles in a gas.
(ii) Complete the sentences below using only the words solid, liquid and gas.
Solidification occurs when a …………………………….. turns into a …………………………….. .
Condensation occurs when a …………………………….. turns into a …………………………….. .
(iii) State the melting point and the boiling point of water at standard atmospheric pressure.
melting point = ……………….. °C
boiling point = ………………… °C
(c) In another lesson, the student builds an electric circuit.
Fig. 12.3 shows the circuit diagram.
(i) State the name of the components represented by the symbols in Table 12.1.
(ii) When there is a potential difference of 6V across the lamp, a current of 0.3A passes through the lamp.
Calculate the resistance of the lamp.
resistance = …………………………………………….. Ω
▶️Answer/Explanation
Ans: 12(a) cooled ;
warmed ;
convection ;
all correct ;
12(b)(i)
random arrangement and widely spaced ;
12(b)(ii) liquid and
solid ;
gas and
liquid ;
12(b)(iii) 0 °C and 100 °C ;
12(c)(i) ammeter ;
voltmeter ;
12(c)(ii) R = V ÷ I (symbols or words) or 6 ÷ 0.3 ;
R = 20 (Ω) ;
Question
(a) A torch (flashlight) contains four cells, a lamp, and a switch connected in series.
(i) Draw a circuit diagram for the torch using standard electrical symbols.
▶️Answer/Explanation
The circuit diagram should include:
- Four cells connected in series.
- A lamp connected in series with the cells.
- A switch connected in series with the lamp and cells.
The standard symbols for cells, lamp, and switch should be used.
(ii) The potential difference (p.d.) across the lamp is 6.0 V when the switch is closed. The resistance of the lamp is 5.0 Ω when lit. Calculate the current in the lamp.
▶️Answer/Explanation
Using Ohm’s Law: \( V = IR \), where \( V \) is the potential difference, \( I \) is the current, and \( R \) is the resistance.
Given: \( V = 6.0 \, \text{V} \), \( R = 5.0 \, \Omega \)
\( I = \frac{V}{R} = \frac{6.0}{5.0} = 1.2 \, \text{A} \)
The current in the lamp is 1.2 A.
(iii) Two lamps each of resistance 5.0 Ω are connected together in a series circuit. Calculate the combined resistance of the two lamps in series.
▶️Answer/Explanation
In a series circuit, the total resistance \( R_{\text{total}} \) is the sum of the individual resistances.
Given: \( R_1 = 5.0 \, \Omega \), \( R_2 = 5.0 \, \Omega \)
\( R_{\text{total}} = R_1 + R_2 = 5.0 + 5.0 = 10.0 \, \Omega \)
The combined resistance of the two lamps in series is 10.0 Ω.
(b) Choose words from the list to complete the sentences to describe the energy transfers that occur when the torch is switched on.
You may use each word once, more than once, or not at all.
- chemical
- elastic
- electrical
- gravitational
- light
- nuclear
- sound
- thermal
The energy stored in the cells is …… potential energy. This energy is transferred into …… energy which passes through the lamp. The useful energy from the lamp is …… energy. Some energy is wasted as …… energy.
▶️Answer/Explanation
The energy stored in the cells is chemical potential energy. This energy is transferred into electrical energy which passes through the lamp. The useful energy from the lamp is light energy. Some energy is wasted as thermal energy.
(c) Solar energy is sometimes used to power torches. Solar energy is a renewable energy resource. State two other renewable energy resources.
▶️Answer/Explanation
Two other renewable energy resources are:
- Wind energy – Energy harnessed from the wind using wind turbines.
- Hydropower – Energy generated from the movement of water, typically in dams or rivers.
(d) Fig. 3.1 shows a ray of light from a torch shining on a mirror.
(i) State the name of line XZ.
▶️Answer/Explanation
Line XZ is called the normal. The normal is an imaginary line perpendicular to the surface of the mirror at the point where the light ray strikes the mirror.
(ii) State what happens to the ray of light at point X on Fig. 3.1.
▶️Answer/Explanation
At point X, the ray of light undergoes reflection. According to the law of reflection, the angle of incidence is equal to the angle of reflection, and both angles are measured relative to the normal.