Question

Which of the following actions cannot induce voltage in a wire?

A) moving a coil of wire near a magnet

B) moving a magnet near a coil of wire

C) changing a current in a nearby coil of wire

D) changing the magnetic field around the coil of wire

E) moving a wire parallel to a magnetic field

Answer 1

Answer : The correct option is, E.

Explanation :

Induced voltage : According to Faraday's Law the induced voltage in a coil is directly proportional to the number of turns in the coil and to the rate at which magnetic field is changing.

Formula for induced voltage :

$e=N\frac{d\phi}{dt}$

where,

e = induced voltage

N = number of turns in a coil

$\phi$ = magnetic flux

t = time

Magnetic flux : Magnetic flux is measure the magnetic field within a closed area.

Formula used for magnetic flux :

$\phi=BAcos\theta$

where,

B = magnetic field

A = area

$\theta$ = angle between the magnetic field and the area of loop

Only option (E) can not induced voltage in a wire because when moving a wire parallel to a magnetic field then the $\theta$ will be zero, so $cos\theta$ will become 1. Hence, the flux becomes constant.

As, the flux is a constant value for this, so, the induced voltage becomes 0 because $\frac{d\phi }{dt}=0$. So, it will not induced voltage.

Answer 2

Answer:

For plato users: Option E.

Explanation: