Welcome to the section of Second Law of Thermodynamics. The section is a step ahead of the First Law and develops a better understanding of the various processes in Thermodynamics. This law also introduces a new property "Entropy".

Important formulas:

Cyclic Heat Engine:

• $W=Q_{1}-Q_{2}$
• $\eta=\frac{W}{Q_{1}}=1-\frac{Q_{2}}{Q_{1}}$

Refrigerator:

$COP_{R}=\frac{Q_{2}}{W}=\frac{Q_{2}}{Q_{1}-Q_{2}}$

Heat Pump:

• $COP_{P}=\frac&space;{Q_{1}}{W}$
• $COP_{P}=COP_{R}+1=\frac{1}{\eta}$

Carnot principles:

• $\eta_{rev}>\eta_{irrev}$
• $\eta_{rev-1}=\eta_{rev-2}$

Claussius Theorem:

• $\oint_{R}{\frac{dQ}{T}}=0$
• For Carnot cycle:   $\frac&space;{Q_{1}}{T_{1}}=\frac&space;{Q_{2}}{T_{2}}$