## November 28, 2014

### Junior Inter Physics Important Questions for AP and Telangana

Q: Define thermal equilibrium. How does it leads to Zeroth law of
thermodynamics?
A: Two systems are said to be in thermal equilibrium, if the
temperature of two systems are equal and there is no net flow of heat
between them, when they are brought into thermal contact.
Zeroth law: If two systems are in thermal equilibrium with a third
system separately, then they must be in equilibrium with each other.

Q: What thermodynamic variables can be defined by a) Zeroth law b) First law.
A: In Zeroth law of thermodynamics temperature is a thermodynamic variable.
In first law of thermodynamics internal energy is a thermodynamic variable.

Q: How much will be the internal energy change in
1) Isothermal process 2) Adiabatic process
A: There is no change in the energy of an ideal gas in an isothermal
process. i.e., ΔU = 0
For an adiabatic process ΔQ = 0
ΔU = − ΔW
Work done by the gas results in its internal energy.