Q. A coil of 1000 turns is wound on a book and this book is lying on the table. The vertical component of earth’s magnetic field is $0.6 \times 10^{- 4}$ T and the area of the coil is 0.05 $m^{- 2}$. The book is turned over once about a horizontal axis is 0.1 s. This average emf induced in the coil is
A) 0.03 V
B) 0.06 V
C) Zero
D) 0.6 V
Explanation
(b) $e = \ \frac{- d\phi}{dt} = \ \frac{- NBA(\cos{0{^\circ} - \cos 180{^\circ})}}{dt}$
= $\frac{2\ NBA}{dt} = \ \frac{2 \times 1000 \times 0.6 \times 10^{- 4} \times 0.05\ }{0.1}$
= 0.06 V
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.