Question

The Transformer voltage induced in the secondary coil of a transformer is mainly due to:
A. a varying electric field
B. a varying magnetic field
C. the vibrations of the primary coil
D. the iron core of the transformer

Answer 1

Hint-A transformer is a device that uses the process of electromagnetic induction to transfer electrical energy from one circuit to another. It can be used to increase the level of voltage or decrease the level of voltage between circuits.
Principle of transformer: A transformer works on the principle of mutual induction. When there is a change in current in the primary coil the magnetic flux linked with the secondary coil changes which induces an EMF in the secondary coil.

Step by step solution:
A transformer is a device that uses the process of electromagnetic induction to transfer electrical energy from one circuit to another. It can be used to increase the level of voltage or decrease the level of voltage between circuits.

A basic transformer consists of four primary parts.
1. input connection
2. output connection
3. core
4. the windings.

Transformers have two windings, a primary winding and a secondary winding. The number of turns in the primary winding is denoted as ${N_P}$.The number of turns in the secondary winding is denoted as ${N_S}$. Voltage given to the primary winding is represented as ${V_P}$ and voltage that we get at the secondary winding is represented as ${V_S}$. Then, the transformer equation is given by
$\dfrac{{{V_P}}}{{{V_S}}} = \dfrac{{{N_P}}}{{{N_S}}}$

Principle of transformer: A transformer works on the principle of mutual induction. When there is a change in current in the primary coil the magnetic flux linked with the secondary coil changes which induces an EMF in the secondary coil.
The working of the transformer itself depends on change in current in the primary coil. DC sources which produce a constant current cannot be used since they cannot produce a varying magnetic field. Therefore, EMF cannot be induced in the secondary coil

Thus, it is the change in magnetic field that induces emf in the secondary coil. So, we can say that the transformer voltage induced in the secondary coil of a transformer is mainly due to a varying magnetic field.

So, the correct answer is option B.

Note: A transformer can work only on AC and the output is also an AC voltage which will be stepped up or down depending upon the number of turns in the primary and secondary coil. In step up transformers we get a higher AC voltage at the output than the input AC voltage. In such a type of transformer, the number of turns in the secondary winding will be greater than the number of turns in the primary winding. In the step down transformer we get a low AC voltage at the output. In such a transformer the number of turns in the secondary winding will be less than the number of turns in the primary winding.