How the results are made
Each run takes a metal from AQA’s handbook table and a heater of 30 to 110 W (the handbook’s range), adds up to 7% for energy lost to the room, and rises a whole number of tenths of a degree each minute, so the straight part reads cleanly. The first readings lag behind the line, as a real block does while it warms through. Answers that depend on your line of best fit are right within 5%.
Example
In set HEAT2A (GCSE), a 2.00 kg copper block is heated at 12.5 V and 3.6 A, so P = 45 W. Between minute 2 and minute 9 the heater transfers 45 × 420 = 18 900 J and the line of best fit rises 23.8 °C, so c = 18 900 ÷ (2.00 × 23.8) = 397 J/kg °C. That is a little above the 385 J/kg °C in AQA’s handbook table, because some energy heats the room. Open set HEAT2A
Questions
How do you find specific heat capacity from a graph?
On a graph of temperature against energy, take the gradient of the straight part. The heat capacity is 1 ÷ gradient, and c = heat capacity ÷ mass. On a graph against time, find the energy as power × time.
Why is the start of the graph curved?
The heater and the block take time to warm through before the thermometer rises steadily. Use only the straight part of the graph.
Why is my value higher than the true value?
Some of the heater’s energy warms the air and the bench, but the calculation counts all of it. The temperature rises less than it should, so c comes out too high. Insulation reduces this.
How do you work out the energy transferred?
Power = potential difference × current, then energy = power × time, with the time in seconds. A 30 W heater on for 7 minutes transfers 30 × 420 = 12 600 J.
What are the specific heat capacities of the metals?
AQA’s practical handbook lists aluminium 913, iron 500, copper 385 and lead 126 J/kg °C.
Why put water in the thermometer hole?
A drop of water fills the air gap around the thermometer, so it touches the block properly and reads its temperature, not the air’s.
Sources, checked October 25, 2026: AQA GCSE Physics 8463 specification, version 1.1 (September 30, 2019); AQA GCSE Physics practical handbook, version 5.0 (March 2018), specific heat capacity; OpenStax Chemistry 2e, 5.1 Energy Basics (Table 5.1), 5.2 Calorimetry and 10.3 Phase Transitions (Flowers et al., Rice University, 2019, CC BY 4.0; specific heats of water and the metals and the enthalpies of water used here).