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.

A step up transformer with 150 turns primary and 1500 turns in secondary works at 95% efficiency. The primary draw a current 2.5A when connected to 220V a.c. Calculate the current and voltage in secondary.

The turns-ratio of a step up transformer is 1:10 and a current of 1.5 A is passed through the primary at 220 V. Obtain the values of voltage and the current in the secondary.

A hot plate of an electric oven connected to a 220V line has two resistance coils A and B, each of 24Omega resistance, which may be used separately, in series, or in parallel. What are the currents in the three case? Amount of current when the coils are used separately.