A 1.0 kg aluminium block is heated. The heater transfers 18000 J and the temperature rises from 20°C to 40°C. Calculate the specific heat capacity of aluminium.
[3 marks]
Total for this question: 3
Physics required practicals
Specific heat capacity
AQA 4.1 · RP1
GCSE Physics (8463) · Required practical 1 — method, variables, the marks examiners report students losing.
Board and spec code confirmed against AQA 8463 · registry checked 2026-07-17How this checking works
Determine the specific heat capacity of a material by linking the electrical energy transferred to a block to its rise in temperature (E = m x c x change in temperature).
Apparatus
- Metal block (e.g. aluminium) with holes for a heater and thermometer
- Immersion (electric) heater and low-voltage power supply
- Joulemeter, or an ammeter, voltmeter and stopwatch
- Thermometer (or temperature sensor)
- Balance, and insulation to wrap the block
Method
- 1Measure the mass of the block in kilograms on a balance.
- 2Wrap the block in insulation and put the heater and thermometer into their holes (a drop of oil in the thermometer hole improves thermal contact).
- 3Record the starting temperature.
- 4Switch on the heater and start the stopwatch; read the potential difference V and current I (or read the joulemeter).
- 5Heat for a measured time t, then switch off; keep watching the thermometer and record the highest temperature reached (energy is still spreading through the block).
- 6Energy transferred E = V x I x t; specific heat capacity c = E / (m x change in temperature).
Results & processing
- Calculate c = E / (m x change in temperature), with mass in kg and energy in J, giving c in J/kg°C.
- For a better value, record temperature against energy supplied and take the gradient: gradient = 1 / (m x c).
Where students lose marks
Reading the temperature the moment the heater is switched off.
Fix: There is a thermal lag — keep watching and record the highest temperature the block reaches, so the temperature rise matches the energy supplied.
Not insulating the block.
Fix: Without insulation some energy is lost to the surroundings, so the calculated c comes out too high; lag the block to reduce this.
Leaving the mass in grams.
Fix: Convert mass to kilograms before using c = E / (m x change in temperature), or the answer is out by a factor of 1000.
Improve the method
- Insulate the block well to cut energy lost to the surroundings.
- Put a little oil in the thermometer hole for good thermal contact.
- Take the highest temperature reached after switching off, and repeat the experiment.
Try it — exam-style
Medium
ORIGINAL
Medium
ORIGINAL
A student's measured specific heat capacity is higher than the true value. Explain why, and state one improvement.
[2 marks]
Total for this question: 2
Questions are written in the style of past AQA papers — never copied from them.
Drill it properly
Stuck on specific heat capacity?
Specific-heat questions are lost on the thermal-lag reading and unit conversions, not the physics — I drill both. Free intro call, then a free first lesson.