If ∆U and ∆W represent the increase in internal energy and work done by the system respectively in a thermodynamical process, which of the following is true?

Options

(a) ∆U = – ∆W, in an adiabatic process
(b) ∆U = ∆W, in an isothermal process
(c) ∆U = ∆W, in an adiabatic process
(d) ∆U = – ∆W, in an isothermal process

Correct Answer:

∆U = – ∆W, in an adiabatic process

Explanation:

BY first law of thermodynamics, ∆Q = ∆U + ∆W
In adiabatic process, ∆Q = 0 ∆U = – ∆W
In isothermal process, ∆U = 0 ∆Q = ∆W