Efficiency of a transformer is equal to

A Efficiency of transformer = (secondary coil à· primary coil) à— 100%
B Efficiency of transformer = (mechanical advantage ÷ velocity ratio) × 100%
C Efficiency of a transformer = (Number of turns in the secondary coil à· Number of turns in the primary coil) à— 100%
D Efficiency of a transformer = (power developed in the secondary coil à· power supplied to the primary coil) à— 100%

Correct Answer: Option D

Explanation:
Efficiency of a transformer = (power developed in the secondary coil Ã· power supplied to the primary coil) Ã— 100%