Question

The turn ratio of transformers is given as 2: 3. If the current through the primary
The coil is 3 A, thus calculating the current through load resistance.
(A) 1 A
(B) 4.5 A
(C) 2 A
(D) 1.5 A

Answer 1

Hint We know that a transformer is a static electrical machine which transfers AC electrical power from one circuit to the other circuit at the constant frequency, but the voltage level can be altered that means voltage can be increased or decreased according to the requirement. Transformers are electrical devices consisting of two or more coils of wire used to transfer electrical energy by means of a changing magnetic field. A transformer is built to transfer the energy from one circuit into another circuit by way of magnetic coupling. An alternating current creates a magnetic flux in the core on its way through the first winding, inducing the voltage in the others. It can convert high and low voltages; it cannot convert AC to DC

Complete step by step answer
We know that the transformation ratio is defined as the ratio of secondary voltage to the primary voltage. It can also be defined as the ratio of number of turns in the secondary winding to the number of turns in the primary winding.
We can conclude that transformer turns ratio is the division of the number of turns in the primary winding by the number of turns in the secondary winding by the equation $T_{\mathrm{R}}=\mathrm{N}_{\mathrm{p}} / \mathrm{N}_{\mathrm{s}}$.
This ratio should also equal the voltage of the primary winding divided by the voltage of the secondary winding, as given by $\mathrm{V}_{\mathrm{p}} / \mathrm{V}_{\mathrm{s}}$.
If $i_{s}$ and $i_{p}$ be the currents in the primary and secondary at any instant and the energy losses by zero, then Power in secondary = power in primary $V_{s} \times i_{s}=V_{p} \times i_{p}$
$\Rightarrow \dfrac{i_{p}}{i_{s}}=\dfrac{V_{s}}{V_{p}}=\dfrac{N_{s}}{N_{p}}=$ transformer ratio
Given $, \dfrac{N_{p}}{N_{s 0}=\dfrac{2}{3}, i_{p}=3 A}$
$\Rightarrow i_{s}=\dfrac{N_{p}}{N_{s}} i_{p}=\dfrac{2}{3} \times 3=2 A$

Hence, we can say that option C is correct.

Note: We should know that the main principle of operation of a transformer is mutual inductance between two circuits which is linked by a common magnetic flux. A basic transformer consists of two coils that are electrically separate and inductive, but are magnetically linked through a path of reluctance.
Thus, we can say that transformers have two windings, being the primary winding and the secondary winding. The primary winding is the coil that draws power from the source. The secondary winding is the coil that delivers the energy at the transformed or changed voltage to the load. Generally, the primary winding of a transformer is connected to the input voltage supply and converts or transforms the electrical power into a magnetic field. While the job of the secondary winding is to convert this alternating magnetic field into electrical power producing the required output voltage.