Q. 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 $\overrightarrow{V} = v\ \overrightarrow{i}$. The magnetic field is directed along the negative $z$-axis direction. The induced $emf$, during the passage of these loops, out of the field region, will not remain constant for
A) The rectangular, circular and elliptical loops
B) The circular and the elliptical lops
C) Only the elliptical loop
D) Any of the four loops
Explanation
(b) $|e| = \frac{d\phi}{dt} = \frac{BdA}{dt}$
Now, as the square loop and rectangular loop move out of magnetic field, $\frac{dA}{dt}$ is constant, therefore $|e|$ is constant. But in case of circular and elliptical loops, $\frac{dA}{dt}$ changes. Therefore, $|e|$ does not remain constant
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.