Question

A rectangular, a square, a circular and an elliptical loop, all in the (x-y) plane, are moving out of a uniform magnetic field with a constant velocity, $\overrightarrow V = v \cdot \hat i$. The magnetic field is directed along the negative z-axis direction. The induced emf, during the passage of these loops, come out of the field region, will not remain constant for:
A. Any of the four loops
B. The rectangular, circular and elliptical loops
C. The circular and the elliptical loops
D. Only the elliptical loop

Answer 1

The area coming out through the circular and elliptical loop is not uniform throughout the magnetic field whereas the area coming out through the square and rectangular loop is uniform throughout the magnetic field.

Complete step by step answer:
The area coming out through the square loop is uniform throughout the magnetic field, the induced emf will also be constant through the square loop.
The area coming out through the rectangular loop is uniform throughout the magnetic field, the induced emf will also be constant through the rectangular loop.
The area coming out through the circular loop is not uniform throughout the magnetic field, the induced emf will not be constant through the circular loop.
The area coming out through the elliptical loop is not uniform throughout the magnetic field, the induced emf will not be constant through the elliptical loop.

Since the area coming out through the circular and elliptical loop is not uniform throughout the magnetic field, the induced emf will also not be constant through the circular and elliptical loop.

So, the correct answer is “Option C”.

Note: In a rectangular and a square loop the magnetic flux change is constant over some constant period of time whereas in circular and elliptical loop the magnetic flux change is constant over some constant period of time.