A thermodynamic system undergoes cyclic process ABCDA as shown in figure. The work done by the system in the cycle is

In a cyclic process work done is equal to the area under the cycle and is positive if the cycle is clockwise and negative if anticlockwise. As is clear from figure, WAEDA=+ area of ∆AED=+12P0V0 WBCEB=-Area of ∆BCD=-12P0V0The network done by the system isWnet =WAEDA+WBCEB=+12P0V0-12P0V0= zero