In: Physics
The figure below displays a circular loop of nickel wire in a uniform magnetic field pointing into the page. The radius of the loop is 10.0 cm and the magnitude of the field is 0.160 T. You grab points A and B and pull them in opposite directions, stretching the loop until its area is nearly zero, taking a time of 0.210 s to do so. What is the magnitude of the average induced emf in the loop (in mV) during this time?
The radius of the loop is r=10cm=0.10m
The area of the loop is
The magnetic flux passing through the loop in presence of uniform magnetic field is
where is the angle that the magnetic field makes with the normal of the loop. It is given that the magnetic field is perpendicular to the loop,
When the area is reduced to zero, the magnetic flux passing through the loop is zero
Given the change in flux takes place in time , the average induced emf in the loop is
Substituting given values
Using 10-3V=1mV we get