Which of the following is an application of Eddy currents?
I. Magnetic braking in trains
II. Electromagnetic damping
III. Electric power meters

Correct option is C

The correct answer is (c) I, II, and III.
Eddy currents have several practical applications due to their ability to create resistance and generate magnetic fields. Here are some key applications:
1. Magnetic Braking in Trains: Eddy currents are used in magnetic braking systems, particularly in high-speed trains. When a magnetic field interacts with the metal wheels or rails, it induces eddy currents that create a resistive force, slowing down the train without physical contact.
2. Electromagnetic Damping: Eddy currents are used in damping mechanisms, where they oppose the motion of moving parts, thus reducing vibrations and providing stability. This principle is used in devices like galvanometers to control the oscillation of the needle.
3. Electric Power Meters: Eddy currents are used in electric power meters (also known as watt-hour meters) to measure the consumption of electricity. The rotating disc inside these meters is subjected to eddy currents, which interact with magnetic fields to provide a reading of energy usage.
Information Booster: ● Eddy currents are circular currents induced within conductors when they experience a changing magnetic field. ● They produce heat and resistance, making them useful in induction heating and braking systems. ● Magnetic braking is advantageous because it reduces wear and tear, as it does not require contact. ● Electromagnetic damping provides smooth operation in instruments like galvanometers. ● Power meters use eddy currents to accurately measure electric power consumption.