Expert Film: Specific Heat Capacity of Aluminium Experiment - GCSE Physics Required Practical. A further source of error comes from using a joulemeter. The joulemeter measures the power going into the power supply. Some power may be lost inside the power supply and not all of it will go into the heater. Watch the next 2 videos to research an alternative method that reduces these errors. Write a method to expand on how this can be used to calculate specific heat capacity. Use this to help you answer the questions on the handout.