Question

State the underlying principle of a transformer. How is the large scale transmission of electric energy over long distances done with the use of transformers?

Answer 1

Hint: A transformer is a device which is used to transfer electrical energy from one circuit to another. Its working is based on the mutual induction of two coils placed in vicinity of each other.

Complete step by step solution:
A transformer is an electrical device which is used to couple one circuit to another. The transformer transforms the electrical energy from one circuit to another.
A transformer is constructed using two coils wound around a laminated steel core. All the components are electrically insulated from one another.
The basic working principle of a transformer is mutual inductance between the coils of the transformer. In a transformer, we have a primary coil and a secondary coil. An input signal is fed to the primary coil. The change in flux in secondary coil due to flow of current in primary coil induces an e.m.f in secondary coil. The amount of e.m.f produced in the coils depends on the number of windings of the coils.
On the basis of windings, we have two types of transformers:

1) Step-down transformer: The primary coil has more windings than secondary coil. It decreases or steps down the voltage.

2) Step-up transformer: The secondary coil has more windings than primary coil. It increases or steps up the voltage.

Electricity is transmitted over long distances at high voltage in order to reduce resistance offered by cables. In order to increase the voltage, a step-up transformer is used before transmitting and a step-down transformer is used to lower the voltage at the receiving station.

Note: We use a laminated steel core in a transformer because it reduces losses due to eddy currents. Eddy currents are currents which are set up in a conductor due to changing magnetic fields around it. They are not useful and lead to loss of energy.