Write the sign convention for internal energy in thermodynamics.

(N/A) In thermodynamics,the sign convention for internal energy change $(\Delta U)$ is based on the First Law of Thermodynamics: $\Delta U = Q - W$.
$1$. If the internal energy of the system increases,$\Delta U$ is positive $(+ve)$. This typically occurs when heat is added to the system or work is done on the system.
$2$. If the internal energy of the system decreases,$\Delta U$ is negative $(-ve)$. This typically occurs when heat is released by the system or the system does work on the surroundings.
$3$. For an ideal gas,the internal energy depends only on temperature. Therefore,if the temperature of an ideal gas increases,$\Delta U > 0$,and if the temperature decreases,$\Delta U < 0$.