A hydroelectric power plant situated at a distance of 20 km from a town. Whose energy demand is 100 MW at 240 V. At hydro electric power plant, the water pressure head is at a height of 400 m and the water flow available is 100 m³/s. Electrical energy generated in power plant is transmitted to the town with the use of transformers voltage output of the Ac. generator at power plant is stepped up and is there transmitted over long distances to an sub-station near the consumers in town. Sub-stations and utility poles steps down the voltage finally the 240 V which finally reaches the houses.

In ideal transformer back emf (ep) in primary coil is equal to the applied voltage (Vp) across primary coil. If this were not so then.

Primary current would be infinite

The correct answer is Option (3) → Primary current would be infinite

In any coil, applied AC voltage causes current to flow

Which induces a back emf

Thus applied voltage generates a current that gets limited by back emf

If this were not so, there is nothing to impede or block the current and thus primary current will become infinite.