Question

A loop of wire is in a magnetic field such that its axis is parallel with the field direction. Which of the following would result in an induced emf in the loop? Choose all that apply.1.Moving the loop outside of the magnetic field region.2.Spin the loop such that its axis does not consistently line up with the magnetic field direction.3.Change the magnitude of the magnetic field.4.Change the diameter of the loop

Answer 1

Answer:

All the 4 options

Explanation:

Electromagnetic induction occurs when the magnetic flux through a coil of wire is changing over time:

$\epsilon = -\frac{\Delta \Phi}{\Delta t}$

where

$\epsilon$ is the emf induced in the coil

$\Delta \Phi$ is the variation of magnetic flux

$\Delta t$ is the variation of time

The presence of an emf in the coil will generated an induced current.

The magnetic flux through the coil is given by

$\Phi = BA cos \theta$

where

B is the intensity of the magnetic field

A is the area of the coil

$\theta$ is the angle between the direction of the field and the axis of the coil

We see that any actions that changes one of these 3 variables will change the magnetic flux through the coil, so it will also induce a current.

The 4 options are:

1.Moving the loop outside of the magnetic field region. --> this will decrease the intensity of the magnetic field, B, therefore it will change the flux, and it will induce a current

2.Spin the loop such that its axis does not consistently line up with the magnetic field direction. --> this will change the angle between the direction of the coil's axis and the field B, so this will also change the flux, and therefore will induce a current

3.Change the magnitude of the magnetic field. --> this will change the magnitude of B, so this will also change the flux, and therefore will induce a current

4.Change the diameter of the loop --> this will change the area of the coil A, so this will also change the flux, and therefore will induce a current

Therefore, all 4 options are correct.