Question

In a step-down transformer, the secondary coil has _______ number of turns.
A) Strength
B) Less
C) Alternating
D) Primary

Answer 1

We can approach the solution by trying to recall the function of a step-down transformer which is to lower the voltage of the supply. It can be achieved by increasing the current and thus lowering the voltage, we know that voltage in a transformer is proportional to the number of turns, hence we can reach the solution easily.

Complete step by step solution:
As told in the hint, we will try to approach the solution to the question by trying to recall the function of a step-down transformer and how it achieves this.
A transformer consists of three basic parts. These are an iron core which provides a circuit of low reluctance for magnetic lines of force, a primary winding or primary coil, which receives the electrical energy from the source of applied voltage, and a secondary winding or secondary coil, which receives electrical energy by induction from the primary coil. The primary and secondary of this closed core transformer are wound on a closed core to obtain maximum inductive effect between the two coils.
To decrease the amount of the voltage, we need to increase the current on the secondary coil. It can be achieved by decreasing the amount of turns in the secondary coil, the concept is to actually decrease the induced voltage by decreasing the number of turns on the secondary coil, a stepped-down voltage is achieved.

Hence, in a step-down transformer there are more turns on the primary coil than the secondary coil.

So, the correct answer is option (B), i.e. In a step-down transformer, the secondary coil has less number of turns.

Note: Many students err in the question by actually misremembering the working of a step-down transformer. If you can reach the point that it lowers the voltage of the supply, you can easily relate it to a lesser number of turns on the secondary coil and gain easy marks in any exam. Vice-versa, a step-up transformer has a higher number of turns on the secondary coil as compared to the primary coil.