In a step down Transformer:

The correct answer is Option (4) → The number of turns in the secondary coil are less than the number of turns in the primary coil

In a transformer the voltage ratio equals the turns ratio, and for an ideal transformer the input power equals the output power.

    \( \displaystyle \frac{V_s}{V_p} = \frac{N_s}{N_p} = \frac{I_p}{I_s} \)

A step-down transformer lowers the voltage, so \( V_s \lt V_p \).

Option (1) The output voltage is greater than the input voltage — Incorrect. A higher output voltage is the property of a step-up transformer.

Option (2) The output power is less than the input power — Incorrect. In an ideal transformer the output power equals the input power.

Option (3) The current in the secondary coil is less than the current in the primary coil — Incorrect. With equal powers, \( V_s I_s = V_p I_p \); a lower secondary voltage means a larger secondary current.

Option (4) The number of turns in the secondary coil are less than the number of turns in the primary coil — Correct. Since \( V_s/V_p = N_s/N_p \), a lower output voltage needs fewer turns in the secondary coil.

NCERT (2026-27):
Transformers – “… If the transformer is assumed to be 100% efficient (no energy losses), the power input is equal to the power output, and since p = i v, … If the secondary coil has less turns than the primary (N_s < N_p), we have a step-down transformer. In this case, V_s < V_p and I_s > I_p. That is, the voltage is stepped down, or reduced, and the current is increased.”