Question

What is an eddy current? Write down its utilities.

Hint:

Eddy currents are minimized (to reduce energy loss) by using \textbf{laminated cores} in electrical machines such as transformers and motors.

Answer 1

Step 1: According to Faraday’s law of electromagnetic induction, any change in the magnetic flux through a conductor induces an electromotive force (emf) in it: \[ \mathcal{E} = - \frac{d\Phi_B}{dt}, \] where \(\Phi_B\) is the magnetic flux.
Step 2: In a bulky or solid conductor (not just a wire loop), this induced emf generates currents that flow in closed loops within the body of the conductor. These circulating currents are called \textit{eddy currents}.
Step 3: Eddy currents produce resistive heating and oppose the change in magnetic flux (Lenz's law), leading to energy loss in the form of heat. Despite this, eddy currents have practical applications, such as:

Damping: They provide electromagnetic damping in galvanometers and meters.
Braking: Used in eddy current brakes in trains and roller coasters for smooth deceleration.
Heating: Employed in induction heating for metal melting and cooking.