OCR GCSE Physics A (Gateway)
OCR GCSE Physics A P3.2 Simple Circuits Exam Questions
Free OCR GCSE Physics A exam questions for P3.2 Simple Circuits, with a mark scheme for every pack. Covers circuit symbols, potential difference, resistance, I-V characteristics, series and parallel circuits, LDRs, thermistors, energy and power in circuits.
P3.2 Simple Circuits exam questions
1 question pack of real past exam questions, each with its mark scheme. Do not stop after a few: answer as many as you can without notes, then mark every answer with the mark scheme. The more questions you do, the more quickly you will spot how examiners ask about each idea.
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About OCR GCSE Physics A P3.2 Simple Circuits
P3.2 completes the P3 Electricity chapter of OCR Gateway Physics A. It covers circuit diagrams and symbols, how to measure current and potential difference, and the relationship V = IR. You need to describe and explain I-V characteristics for a fixed resistor, filament lamp and diode, and how the resistance of LDRs and thermistors depends on light and temperature. The topic compares series and parallel circuits and calculates total resistance in series. It ends with energy transferred and power in circuits. It builds on P3.1 and links to P8.2 Powering Earth. Examiners regularly set multi-step circuit calculations and graph explanation questions.
What you need to know
- Measuring Ammeters are connected in series to measure current; voltmeters are connected in parallel to measure potential difference.
- Resistance Potential difference = current x resistance (V = IR). An ohmic conductor at constant temperature has a constant resistance.
- I-V characteristics Fixed resistor: straight line through the origin. Filament lamp: curve because resistance increases as temperature rises. Diode: current flows in one direction only.
- Sensors The resistance of an LDR decreases as light intensity increases. The resistance of a thermistor decreases as temperature increases.
- Series circuits Current is the same everywhere; the p.d. is shared; total resistance is the sum of individual resistances.
- Parallel circuits Each branch has the same p.d.; branch currents add up to the total; total resistance is less than the smallest individual resistance.
- Energy and power Energy transferred = charge x p.d. = power x time. Power = p.d. x current = (current)^2 x resistance.
Common mistakes in P3.2 Simple Circuits
- Saying current is shared in a series circuit. Current is the same everywhere; the p.d. is shared.
- Saying adding a resistor in parallel increases total resistance. It decreases it.
- Describing a filament lamp graph without explaining it. Say the filament heats up, ions vibrate more and resistance increases.
- Getting LDR or thermistor behaviour backwards.
- Using P = I^2 x R with p.d. instead of current. Check which quantities you are given.
Try three P3.2 Simple Circuits exam-style questions
1. A 12 ohm resistor has a p.d. of 6.0 V across it. Calculate the current and the power. (4 marks)
Show the mark scheme answer
I = V / R = 6.0 / 12; = 0.50 A; P = V x I = 6.0 x 0.50; = 3.0 W.
2. A 4.0 ohm and an 8.0 ohm resistor are connected in series to a 6.0 V battery. Calculate the current. (3 marks)
Show the mark scheme answer
Total resistance = 4.0 + 8.0 = 12 ohms; I = V / R = 6.0 / 12; = 0.50 A.
3. Explain how a thermistor can be used to switch on a heater when a room gets cold. (3 marks)
Show the mark scheme answer
As temperature falls, the thermistor's resistance increases; so the p.d. across it in a potential divider increases; this p.d. is used to switch on the heater circuit.
P3.2 Simple Circuits FAQs
What does OCR GCSE Physics A (Gateway Science) P3.2 Simple Circuits cover?
It covers circuit symbols, current, p.d., resistance, I-V characteristics, series and parallel circuits, LDRs, thermistors, energy and power.
Which paper is P3.2 examined on?
Topics P1 to P4 are assessed on Paper 1 (Foundation) or Paper 3 (Higher), alongside practical skills.
What equations do I need for Simple Circuits?
Learn V = IR, energy transferred = charge x p.d., energy = power x time, P = VI and P = I^2 x R.
