Question

Hysteresis loss and eddy current are used in
A) Induction heating of steel
B) Dielectric heating
C) Induction heating of brass
D) None of the above

Answer 1

Hint: Induction heating is a fast, efficient, and non-contact method for heating electrically conductive materials or semiconducting materials. Hysteresis is a phenomenon that is seen in ferromagnetic substances. It depends on the history of the ferromagnetic substance. According to Lenz’s law, the direction of this induced current is such that it opposes the change which produced it.

Complete step by step answer:
When a ferromagnetic substance is kept in a magnetic field the substance gets magnetized due to induction. In this when the magnetic field intensity (H) changes the magnetic induction (B) does not change in accordance with the change in magnetic field intensity i.e. the magnetic induction also depends on the past history of the substance. Due to this, the magnetic induction lags behind the magnetizing field.
This phenomenon of the lagging of the magnetic induction of the substance behind the magnetizing field is known as hysteresis.
A magnetic field passing through a metallic object changes due to this a current is induced in the metallic object. This induced current is known as eddy current.
Hysteresis loss occurs in ferromagnetic elements and eddy currents are produced due to change in the magnetic field flowing through the material. Hence they will be used in the induction heating of steel.

$\therefore$ Hysteresis loss and eddy current are used in the induction heating of steel. Hence, option (A) correct.

Note:
Option C is easily eliminated as Brass is not a magnetic substance.
The following are the Uses of eddy current.
1) They are used in electric brakes.
2) They are also used in speedometer.
3) Nowadays they are also used in induction heating and induction motors.