First law of thermodynamics for cyclic process
Internal energy changes in the cyclic process, dU = 0. Therefore, according to the first law, q = w. Hence from the energy conservation principle, heat is completely converted into work for the cyclic process.
Work done in isothermal process
Internal energy change in the isothermal process for the ideal gas, dU = ncvdT = 0. Therefore, q = w. Hence, thermodynamics heat is completely converted into work for the ideal gas in the isothermal process.
Energy change in isochoric process
Volume change in isochoric process, dV = 0. From the energy conservation principle, q = dU = ncvdT. Therefore, energy change to an isochoric process only increases the internal energy or temperature of the system.