Two in-phase, 50Hz sinusoidal waveform of unit amplitude are fed into channel-1. and channel-2 respectively of an oscilloscope, Assuming that the voltage scale, time scale and other settings are exactly the same for both the channels. What would be observed if the oscilloscope is operated in x-y mode?

The line to line input voltage to the $$3$$ phase, $$50$$ Hz, ac circuit shown in fig is $$100$$ $$V$$ $$r.m.s$$ Assuming that the phase sequence is $$RYB$$ the wattmeter would read.

A $$415$$ $$V,$$ $$2$$ pole, $$3$$ phase, $$50$$ $$Hz,$$ star connected, non-salient pole synchronous motor has synchronous reactance of $$2\,\Omega $$ per phase and negligible stator resistance. At a particular field excitation, it draws 20 A at unity power factor from a $$415$$ $$V,$$ $$3$$ phase, $$50$$ $$Hz$$ supply. The mechanical load on the motor is now increased till the stator current is equal to $$50$$ $$A.$$ The field excitation remains unchanged. Determine:
$$(a)$$ the per phase open circuit voltage $${E_0}$$
$$(b)$$ the developed power for the new operating condition and corresponding power factor.

The flux per pole in a synchronous motor with the field circuit ON and the stator disconnected from the supply is found to be $$25$$ $$mWb.$$ When the stator is connected to the rated supply with the field excitation unchanged, the flux per pole in the achine is found to be $$20$$ $$mWb$$ while the motor is running on no load. Assuming no load losses to be zero, the no load current down by the motor from the supply