A student carries out an investigation using a solid aluminium block with a mass of 0.80 kg to determine the thermal energy required to increase its temperature by 20 ∘C20\text{ }^\circ\text{C}20 ∘C.
An electrical immersion heater connected to a low-voltage power supply is used to heat the aluminium block.
Describe a practical procedure the student should follow to carry out this experiment safely and accurately, including any measurements they must record.
In your response, calculate the theoretical change in thermal energy required to produce this temperature increase for the 0.80 kg block of aluminium, given that its specific heat capacity is 900 J/kg ∘C900\text{ J/kg }^\circ\text{C}900 J/kg ∘C.