Question

A generator does work on an electric heater by forcing an electric current through it. Suppose 1 kJ of work is done on the heater and in turn 1 kJ of energy as heat is transferred to its surroundings. What is the change in internal energy of the heater?

Answer 1

Answer:

-2 kJ.

Explanation:

Given:

∆Q = 1 kJ

W = 1 kJ

Using the first law of thermodynamics in application to conservation of energy,

∆U = ∆Q - W

Where,

∆U = change in internal energy

∆Q = heat supplied to the system

W = workdone by the system

∆U = -1 - 1

= -2 kJ.

Answer 2

Answer:

The change in internal energy of the heater is 0 kJ

Explanation:

∆U = Q - W

Q is quantity of heat transferred = 1 kJ

W is work done on the heater = 1 kJ

Change in internal energy (∆U) = 1 - 1 = 0 kJ