Figure 12 shows the equipment a student used to determine the specific heat capacity of iron. The iron block the student used has two holes, one for the heater and one for the thermometer. Power supply Figure 12. OJ Suggest why. Joulemeter Heater Thermometer Iron block 0:00 Stopclock Before the power supply was switched on, the thermometer was used to measure the temperature of the iron block. The student left the thermometer in the iron block for a few minutes before recording the initial temperature.