Course: Combined Science + Separate Physics | 20 questions | ← All quizzes
Write A, B, C or D for each question, then tap Show answer to mark it.
Q1 (F, recall) Which component’s resistance decreases as the light intensity increases?
A. Thermistor
B. Diode
C. LDR
D. Filament lamp
Show answer
✅ C. LDR (light-dependent resistor)
Examiner tip: a thermistor’s resistance depends on temperature, not light. Don’t mix them up.
Q2 (F, definition) What is electric current?
A. The energy transferred per unit charge
B. The opposition to the flow of charge
C. The number of electrons in a wire
D. The rate of flow of electric charge
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✅ D
A is potential difference and B is resistance.
Examiner tip: current is measured in amperes (A); 1 A = 1 coulomb per second.
Q3 (F, calculation) A current of 0.50 A flows for 2.0 minutes. How much charge flows?
A. 1.0 C
B. 240 C
C. 0.25 C
D. 60 C
Show answer
✅ D. 60 C
Convert: 2.0 minutes = 120 s
F: Q = I t
I: Q = 0.50 × 120
A: 60 C
Examiner tip: 1.0 C comes from leaving the time in minutes. Time must be in seconds.
Q4 (F, calculation) A current of 0.20 A flows through a 30 Ω resistor. What is the potential difference across it?
A. 6.0 V
B. 150 V
C. 0.0067 V
D. 30.2 V
Show answer
✅ A. 6.0 V
F: V = I R
I: V = 0.20 × 30
A: 6.0 V
Q5 (F, recall) What colour is the earth wire in a UK plug?
A. Brown
B. Green and yellow
C. Blue
D. Black
Show answer
✅ B. Green and yellow
Live is brown and neutral is blue.
Examiner tip: the earth wire is a safety wire. It only carries a current if there is a fault.
Q6 (F, recall) What are the frequency and potential difference of the UK mains supply?
A. 12 V, 50 Hz
B. 230 V, 60 Hz
C. 230 V, 50 Hz
D. 110 V, 50 Hz
Show answer
✅ C. 230 V, 50 Hz
UK mains is an alternating current (a.c.) supply.
Q7 (F, application) Two identical lamps are connected in series to a 12 V battery. What is the potential difference across each lamp?
A. 12 V
B. 6 V
C. 24 V
D. 3 V
Show answer
✅ B. 6 V
In series, the supply p.d. is shared between the components. The lamps are identical, so they share it equally.
Examiner tip: in parallel, each lamp would have the full 12 V.
Q8 (F, calculation) A kettle connected to the 230 V mains draws a current of 10 A. What is its power?
A. 23 W
B. 0.043 W
C. 240 W
D. 2300 W
Show answer
✅ D. 2300 W
F: P = V I
I: P = 230 × 10
A: 2300 W (2.3 kW)
Q9 (F/H, calculation) A 2.0 kW hairdryer is used for 30 s. How much energy does it transfer?
A. 60 000 J
B. 60 J
C. 15 J
D. 67 J
Show answer
✅ A. 60 000 J
Convert: 2.0 kW = 2000 W
F: E = P t
I: E = 2000 × 30
A: 60 000 J
Examiner tip: 60 J means the kW weren’t converted to W.
Q10 (F/H, graph) The I–V graph for a component is a straight line through the origin. At 6.0 V, the current is 0.30 A. Which statement is correct?
A. The resistance increases as the current increases
B. The component only conducts in one direction
C. The resistance is constant at 20 Ω
D. The resistance is 1.8 Ω
Show answer
✅ C
A straight line through the origin means current is directly proportional to p.d., so the resistance is constant (an ohmic conductor).
F: V = I R, so R = V ÷ I
I: R = 6.0 ÷ 0.30
A: 20 Ω
Examiner tip: A describes a filament lamp and B describes a diode.
Q11 (F/H, practical) In the practical to investigate how the length of a wire affects its resistance, why should the current be switched off between readings?
A. To save the battery
B. To stop the wire heating up and changing its resistance
C. So the ammeter can reset
D. To make the p.d. larger
Show answer
✅ B
The resistance of a wire increases as its temperature increases, so heating would make the results less accurate.
Examiner tip: keeping the temperature constant keeps it a fair test.
Q12 (F/H, application) Another resistor is added in parallel to a circuit. What happens to the total resistance of the circuit?
A. It increases
B. It stays the same
C. It doubles
D. It decreases
Show answer
✅ D. It decreases
The current has an extra path to flow through, so the total current increases for the same p.d.
Examiner tip: the total resistance of resistors in parallel is always less than the smallest individual resistance.
Q13 (F/H, calculation) A 4.0 Ω resistor and an 8.0 Ω resistor are connected in series to a 6.0 V battery. What is the current?
A. 2.25 A
B. 72 A
C. 0.50 A
D. 1.5 A
Show answer
✅ C. 0.50 A
Total resistance = 4.0 + 8.0 = 12 Ω
F: V = I R
I: 6.0 = I × 12
F: I = 6.0 ÷ 12
A: 0.50 A
Examiner tip: in series, add the resistances first.
Q14 (F/H, calculation) 5.0 C of charge passes through a 12 V lamp. How much energy is transferred?
A. 60 J
B. 2.4 J
C. 17 J
D. 0.42 J
Show answer
✅ A. 60 J
F: E = Q V
I: E = 5.0 × 12
A: 60 J
Q15 (H, calculation) A current of 3.0 A flows through a 5.0 Ω resistor. What is the power?
A. 15 W
B. 45 W
C. 225 W
D. 0.60 W
Show answer
✅ B. 45 W
F: P = I² R
I: P = 3.0² × 5.0
F: P = 9.0 × 5.0
A: 45 W
Examiner tip: 15 W means you forgot to square the current – the most common mistake with this equation.
Q16 (F/H, application) Why do step-up transformers increase the potential difference before electricity is sent through the National Grid?
A. To increase the current in the cables
B. To make electricity safe for homes
C. So that no energy is wasted
D. To reduce the current, so less energy is wasted heating the cables
Show answer
✅ D
For the same power, a higher p.d. means a lower current. A lower current heats the cables less, so the system is more efficient.
Examiner tip: C is wrong – some energy is always wasted. Write “less energy is wasted”.
Q17 (F/H, recall) Which statement describes a diode?
A. Its resistance increases as it gets hotter
B. Its resistance decreases in bright light
C. Current flows through it in one direction only
D. Current is directly proportional to p.d.
Show answer
✅ C
A diode has a very high resistance in the reverse direction.
Q18 (F/H, application) A thermistor is used in a thermostat. What happens to its resistance when the room warms up?
A. It decreases
B. It increases
C. It stays the same
D. It drops to zero
Show answer
✅ A. It decreases
A thermistor’s resistance decreases as its temperature increases.
Q19 (H, calculation) A 1.2 kW heater is connected to the 230 V mains. What current does it draw?
A. 0.19 A
B. 5.2 A
C. 276 A
D. 5217 A
Show answer
✅ B. 5.2 A
Convert: 1.2 kW = 1200 W
F: P = V I
I: 1200 = 230 × I
F: I = 1200 ÷ 230
A: 5.2 A (2 s.f.)
Examiner tip: 0.19 A means the kW weren’t converted.
Q20 (S only, application) A plastic rod is rubbed with a cloth and becomes negatively charged. What has happened?
A. Protons moved from the rod to the cloth
B. Electrons moved from the rod to the cloth
C. Electrons moved from the cloth to the rod
D. Positive charge was destroyed in the rod
Show answer
✅ C
The rod gained electrons, so it has an overall negative charge. The cloth lost electrons, so it is left positively charged.
Examiner tip: only electrons move in static electricity. Answers about protons moving score nothing.
Your score
Add up your marks out of 20 and multiply by 5 to get a percentage. Rough guide (not an official grade): 18–20 excellent, grade 8–9 standard | 14–17 grade 6–7 | 10–13 grade 4–5 | under 10 revise the notes and try again.
Answer key (for teachers and printing)
1 C 2 D 3 D 4 A 5 B 6 C 7 B 8 D 9 A 10 C 11 B 12 D 13 C 14 A 15 B 16 D 17 C 18 A 19 B 20 C
Revise: Electricity topic page | Fill the gaps: Electricity | Which equation? Electricity
