Question

In an ideal step down transformer, out of the following quantities, which quantity increases in the secondary coil?

• A. Power
• B. Voltage
• C. Current
• D. Frequency

Hint:

Voltage and current are inversely proportional in an ideal transformer. If it steps the voltage down, it inherently steps the current up. This is why high voltage is used for power transmission (to keep current low and minimize heat loss).

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
We must identify which electrical parameter increases across the secondary coil in an ideal step-down transformer.

Step 2: Detailed Explanation:
Let's analyze the properties of an ideal transformer:
4.

Power: In an ideal transformer, there are no energy losses. Therefore, input power equals output power ($P_{\text{in}} = P_{\text{out}}$). Power remains constant.
5.

Frequency: A transformer operates on mutual induction and does not change the frequency of the alternating current. Frequency remains constant.
6.

Voltage: The very definition of a "step-down" transformer is one that reduces the voltage. Therefore, secondary voltage is lower than primary voltage ($V_s < V_p$).
7.

Current: Because power ($P = VI$) is conserved, a decrease in voltage must be perfectly compensated by a proportional increase in current.
$$V_p I_p = V_s I_s \implies \frac{V_p}{V_s} = \frac{I_s}{I_p}$$
Since $V_p > V_s$, it mathematically guarantees that $I_s > I_p$.

Step 3: Final Answer:
The quantity that increases is Current, matching option (C).