An electronic switch $$S$$ is required to block voltages of either polarity during its OFF state as shown in figure (a). This switch is required to conduct in only one direction during its ON state as shown in the figure (b).

Which of the following are valid realizations of the switch $$s$$?

A three - phase diode bridge rectifier is fed from a $$400$$ $$V$$ $$RMS$$. $$50$$ $$Hz$$, three $$-$$ phase $$AC$$ source. If the load is purely resistive, then peak instantaneous output voltage is equal to

Consider a phase $$-$$ controlled converter shown in figure The thyristor is fired at an angle $$\alpha $$ in every positive half cycle of the input voltage. If the peak value of the instantaneous output voltage equals $$230$$ $$V,$$ the firing angle $$\alpha $$ is close to

The given figure shows a step $$-$$ down chopper switched at $$1$$ $$KHz$$ with a duty ratio $$D = 0.5.$$ The peak - peak ripple in the load current is close to