Calculate current drawn by the primary of a transformer, which steps down 200V to 20V to operate a device of resistance 20ohm. Assume the efficiency of the transformer to be 80%.

How much current is drawn by the primary of a transformer which steps down 220 volts to 22 volts to operate a device with an impedance of 220 Ω ?

In a transistor, the base current is changed by 20muA . This results in a change of 0.02V in base emitter voltage and a change of 2mA in the collector current. .If the transistor is used as an amplifier with load resistance of 5KΩ .Find its voltage gain.

A transformer is used to illuminate a bulvb (36 watt and 12v)_ with the help of 220V mains. If the efficiency of the transformer is 75%, then calculate the current in the primary coil.