Pearson Edexcel GCSE Combined Science · P10

Electricity and circuits

50 revision questions with answers for P10 Electricity and circuits in Pearson Edexcel GCSE Combined Science (spec 1SC0). Practise with flashcards, a topic quiz, a random quiz across the course, 5 crosswords, or read every question and answer below.

All 50 questions and answers

Question 1 · Spec P10.1
Where are an atom's charged particles?
Answer:
Positive protons are in the nucleus; negative electrons surround it; neutrons in the nucleus are uncharged.
Question 2 · Spec P10.2
How do standard ammeter, voltmeter and resistor symbols differ?
Answer:
Ammeter: circle with A; voltmeter: circle with V; resistor: rectangle in the circuit line.
Question 3 · Spec P10.3
How do series and parallel circuits differ?
Answer:
Series circuits have one current path; parallel circuits have branches between common connection points.
Question 4 · Spec P10.4
How must a voltmeter be connected?
Answer:
In parallel across the component being measured.
Question 5 · Spec P10.5
What does potential difference mean?
Answer:
Energy transferred per unit charge; one volt is one joule per coulomb.
Question 6 · Spec P10.6
A charge of 20 C passes through 6 V. Find energy transferred.
Answer:
E = QV = 20 × 6 = 120 J.
Question 7 · Spec P10.7
How must an ammeter be connected?
Answer:
In series with the component whose current is measured.
Question 8 · Spec P10.8
What is current, and what carries it in metals?
Answer:
Rate of charge flow; moving electrons carry charge through metals.
Question 9 · Spec P10.9
State the charge-flow equation.
Answer:
Q = It; charge in coulombs, current in amperes and time in seconds.
Question 10 · Spec P10.9
A current of 0.30 A flows for 40 s. Find charge.
Answer:
Q = 0.30 × 40 = 12 C.
Question 11 · Spec P10.10
What is required for sustained current in a circuit?
Answer:
A closed conducting path and a source of potential difference.
Question 12 · Spec P10.11
Branch currents are 0.25 A and 0.40 A. Find their combined current.
Answer:
0.25 + 0.40 = 0.65 A; charge is conserved at the junction.
Question 13 · Spec P10.12
How does increasing a variable resistor's resistance affect current at fixed supply voltage?
Answer:
Current decreases as total circuit resistance increases.
Question 14 · Spec P10.13
State the potential difference, current and resistance equation.
Answer:
V = IR.
Question 15 · Spec P10.13
A resistor has 9 V across it and 0.30 A through it. Find resistance.
Answer:
R = 9/0.30 = 30 Ω.
Question 16 · Spec P10.14
How is total series resistance found?
Answer:
Add the component resistances.
Question 17 · Spec P10.14
Why does adding a parallel branch reduce total resistance?
Answer:
It provides an additional path for charge, increasing total current at the same voltage.
Question 18 · Spec P10.15
How does current vary between components in series?
Answer:
It is the same through every component.
Question 19 · Spec P10.15
How are potential differences related in series?
Answer:
The component potential differences add to the supply potential difference.
Question 20 · Spec P10.15
Find current through 5 Ω and 10 Ω in series across 12 V.
Answer:
Total resistance = 15 Ω; I = 12/15 = 0.80 A.
Question 21 · Spec P10.17 · Core practical
How is a circuit arranged to measure a component's resistance?
Answer:
Connect an ammeter in series and voltmeter across the component, then calculate R = V/I.
Question 22 · Spec P10.17 · Core practical
How are I-V readings collected for a fixed resistor?
Answer:
Vary the applied voltage and record voltage and current, keeping resistor temperature approximately constant.
Question 23 · Spec P10.18
Why is a filament lamp's I-V graph curved?
Answer:
Increasing current heats the filament, increasing resistance so current rises less rapidly.
Question 24 · Spec P10.18
Describe a diode's I-V behaviour.
Answer:
It allows appreciable current mainly in one direction and has very high resistance in reverse.
Question 25 · Spec P10.19
How does LDR resistance change as light intensity increases?
Answer:
It decreases.
Question 26 · Spec P10.20
How does an NTC thermistor's resistance change as temperature increases?
Answer:
It decreases.
Question 27 · Spec P10.17 · Core practical
How can series and parallel circuits be compared experimentally?
Answer:
Measure branch and supply currents and component voltages in each arrangement, keeping the supply and components comparable.
Question 28 · Spec P10.21
How can temperature's effect on a thermistor be investigated?
Answer:
Change its temperature in controlled steps, measure V and I, calculate resistance and keep other conditions constant.
Question 29 · Spec P10.22
What happens when current passes through a resistor?
Answer:
Electrical energy transfers to the resistor's thermal store and then to surroundings.
Question 30 · Spec P10.24
How do electrons cause heating in a resistor?
Answer:
They collide with lattice ions, transferring energy and increasing vibrations.
Question 31 · Spec P10.25 · Higher only
How can unwanted heating in connecting wires be reduced?
Answer:
Use suitably low-resistance wires to reduce dissipated power.
Question 32 · Spec P10.26
Give an advantage and disadvantage of current's heating effect.
Answer:
It is useful in heaters and kettles but wastes energy or causes overheating in other circuits.
Question 33 · Spec P10.27
State the electrical energy equation using current, voltage and time.
Answer:
E = IVt.
Question 34 · Spec P10.27
A 2 A device operates at 12 V for 30 s. Find energy.
Answer:
E = 2 × 12 × 30 = 720 J.
Question 35 · Spec P10.28
What does electrical power measure?
Answer:
Energy transferred each second, measured in watts.
Question 36 · Spec P10.29
A device transfers 3,000 J in 20 s. Find power.
Answer:
P = E/t = 3,000/20 = 150 W.
Question 37 · Spec P10.31
State the electrical power equation using voltage and current.
Answer:
P = IV.
Question 38 · Spec P10.31
Find power for 230 V and 5 A.
Answer:
P = 230 × 5 = 1,150 W.
Question 39 · Spec P10.31
State the power equation using current and resistance.
Answer:
P = I²R.
Question 40 · Spec P10.31
Find power in 8 Ω carrying 0.50 A.
Answer:
P = 0.50² × 8 = 2.0 W.
Question 41 · Spec P10.32
How do a motor and heater differ in useful energy output?
Answer:
A motor transfers energy mechanically; a heater increases thermal energy stores.
Question 42 · Spec P10.33
Distinguish direct and alternating voltage.
Answer:
Direct voltage maintains polarity; alternating voltage repeatedly changes polarity.
Question 43 · Spec P10.36
State the approximate UK mains frequency and voltage.
Answer:
50 Hz and 230 V; the supply is alternating.
Question 44 · Spec P10.37
What is the live wire's function?
Answer:
It carries the alternating potential difference from the mains supply.
Question 45 · Spec P10.37
What is the neutral wire's function?
Answer:
It completes the circuit and is at or close to earth potential.
Question 46 · Spec P10.38
What is the earth wire's safety role?
Answer:
It provides a low-resistance fault path from a metal case, helping protective devices disconnect the supply.
Question 47 · Spec P10.38
How do fuses and circuit breakers improve safety?
Answer:
They interrupt excessive current, reducing overheating and fault hazards.
Question 48 · Spec P10.39
Why place a switch or fuse in the live wire?
Answer:
Opening it disconnects the appliance from the live supply rather than leaving internal parts live.
Question 49 · Spec P10.40
Give typical potential differences involving live, neutral and earth.
Answer:
Live-neutral and live-earth are about 230 V; neutral-earth is about 0 V.
Question 50 · Spec P10.41
Why is connecting live to earth through a person dangerous?
Answer:
The large potential difference can drive a harmful current through the body.

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