Question

In an isothermal process, the internal energy
1. Always decreases
2. Always increases
3. Increases or decreases
4. Remains constant

Answer 1

Correct Answer - Option 4 : Remains constant

Explanation:

The internal energy of a system is the energy contained within the system. The internal energy of an ideal gas is a function of absolute temperature only.

For an ideal gas, U = f(T) only.

In the case of an isothermal process, there is no change in temperature i.e. ΔT = 0

Change in internal energy is given as:

ΔU = mcΔT

ΔT = 0 ⇒ ΔU = 0

So, internal energy will be constant in the isothermal process.