Question

A 18.5-cm-diameter loop of wire is initially oriented perpendicular to a 1.3-T magnetic field. The loop is rotated so that its plane is parallel to the field direction in 0.18 s . What is the average induced emf in the loop? Express your answer to two significant figures and include the appropriate units.

Answer 1

Answer:

0.2v

Explanation:

Data given,

Diameter=18.5cm

Hence we can calculate the radius as D/2=18.5/2=9.25cm

radius=9.25cm/100=0.0925m

The area is calculated as

$area=\pi r^{2}\\Area=0.0925^{2}*\pi \\Area=0.02688m^{2}$

magnetic field, B=1.3T

time,t=0.18s

The flux is expressed as

$flux=BAcos\alpha$

since the loop is parallel, the angle is 0

Hence we can calculate the flux as

$flux=1.3*0.02688cos(0)\\flux=0.0349Wb$

to determine the emf induced in the loop, we use Faraday law

$E=-N\frac{d(flux)}{dt}\\ E=-0.0349/0.18\\E=0.19V\\E=-0.2v$

Note the voltage is not negative but the negative sign shows the current flows in other to oppose the flux