Specific heat capacity (electrical method)

A/L Physics · G.C.E. Advanced Level · Grades 12–13

Aim

To find the specific heat capacity of a metal block by the electrical method.

Apparatus

• Metal block (0.50 kg) with an immersion heater
• Ammeter and voltmeter (12 V, 4.0 A)
• Thermometer and stopwatch

Method

1. Note P = VI and the starting temperature.
2. Switch on and read the temperature every minute.
3. Work out the temperature rise θ.
4. Plot θ against t; c = P ÷ (m × gradient).

Conclusion

Since Pt = mcθ, θ ∝ t. The gradient = P ÷ mc, which gives c (aluminium ≈ 900 J kg⁻¹ K⁻¹).