Sketch and label the VTC of the circuit of over the range 26 V # vI # 6 V if: (a) the directions of D2 and the D4 are reversed, so that their anodes are now at the top and the cathodes at the bottom;...

Sketch and label the VTC of the circuit of over the range 26 V # vI # 6 V if: (a) the directions of D2 and the D4 are reversed, so that their anodes are now at the top and the cathodes at the bottom; (b) D2 and D4 are removed from the circuit; (c) D2, D4, and R4 are removed from the circuit.