1. Three 100W non-inductive resistors, when connected in star across 400 V, 50 Hz, 3 phase consumes 1600 W. When one of the resistances becomes open, the power consumption is reduced by:
a) half b) one third c) two third d) one fourth
2. The power input to a three phase induction motor is 62 kW. The stator loss is 2 kW. If the rotor is running with a slip of 5%, the total copper loss in the rotor will be:
a) 500 W b) 1000 W c) 1500 W d) 3000 W
3. A transformer has an iron loss of 250 W and full-load copper loss of 1000 W. At what percentage of full-load, the efficiency becomes maximum:
1. The velocity of sound is the least in which of the following medium:
1) Air 2) Water 3) Wood 4) Vacuum
2. Two amplifier stages have voltage gains of 100 and 200. The total decibel voltage gain of the cascaded amplifiers is:
1) 46 dB 2) 86 dB 3) 66 dB 4) 106 dB
3. In the circuit shown, what is the minimum value of RL for which the output voltage will remain constant?
