If at every point of a certain curve , the slope of the tangent equals $${{ - 2x} \over y},$$ the curve is _______.

Consider the chopper circuit of figure. The chopper operates at $$400$$ $$Hz$$ and $$50$$% duty cycle. The load current remains almost ripple free at $$10A.$$ Assuming the input voltage to be $$200V$$ and the devices to be ideal, the turn-off time available to the thyristor $$Th$$ $$M$$ is____________ $$\mu s$$

Figure, show two thyristors each rated $$500A$$ (continuous) sharing a load current. Current through thyristor $$y$$ is $$120A.$$ The current through thyristor $$x$$ will be nearly __________ $$A.$$

A three phase $$ac$$-to-$$dc$$ diode bridge rectifier is supplied from a three-phase, $$440V$$ source. The rectifier supplies a purely resistive load. The average $$dc$$ voltage across the load will be ___________ $$V$$.