Question

Give a few electric flux examples with an explanation.

Answer 1

Electric Flux:

Suppose we consider a vertical loop of wire rotating with angular velocity $\omega$ in a uniform steady magnetic field $\overrightarrow{B}$ acting in the horizontal direction.

If at any time $t$ the normal $\left(\hat{n}\right)$ to the plane of the coil makes an angle $\theta =\omega t$ with $\overrightarrow{B}$ the flux linked with the coil of area $S$ at the instant $t$ would be,

$\varphi =\overrightarrow{B}.\hat{n}S$

$=BS\cos \omega t$

According to Faraday's law of induction, the induced emf in the coil due to the change in magnetic flux is,

$\epsilon =-\frac{d\varphi }{dt}$

Some of the examples that shows the use of the change in the electric flux:

Induction Furnace:

1. The heating effect of eddy current is used in an induction furnace when a substance is heated by placing it in a rapidly changing magnetic field.
2. A High-frequency magnetic field can be used in melting metals or extracting metals from ore.
3. Food can be uniformly cooked by placing it in a region of an intense magnetic field.

Inductor Motor:

1. If a conducting cylinder is placed in a rotating magnetic field it rotates due to the eddy current induced in it.
2. This principle is used in an induction motor.

Electric brakes:

1. If a strong magnetic field is suddenly applied to a rotating conductor the induced eddy current tries to oppose the relative motion between the conductor and the magnetic field.
2. This principle is used in electric brakes.

Galvanometer:

1. In a suspended coil dead-beat galvanometer the coil wound on a light metallic frame moves in a magnetic field and an eddy current is induced in the frame.
2. This current opposes the motion of the frame.
3. The motion of the frame is thus, damped.
4. Such damping is deliberately used in some electrical instruments to control the motion of the moving parts of the instruments.