Correct AnswerB. Electromagnetic induction
Quick Explanation
Most common phone charging pads transfer energy by electromagnetic induction between a transmitter coil in the pad and a receiver coil in the device, often with resonant compensation to improve coupling and efficiency.
Detailed Explanation
Concept & Reasoning
An alternating current in the primary coil produces a time-varying magnetic flux. The receiver coil intercepts part of that flux, inducing an emf according to Faraday's law. Power electronics then rectify/regulate the received energy for battery charging.
How to Solve It in the Exam
Wireless charging pad → coupled coils → induction.
Important Exam PointAlignment and coil separation strongly affect coupling coefficient and efficiency.
Related Revision Path
This question sits in the revision path Building Electrical Services → Emerging Electrical Technologies → Wireless Power Transfer .
