Q. A 50 turns circular coil has a radius of 3 cm, it is kept in a magnetic field acting normal to the area of the coil. The magnetic field $B$ increased from 0.10 to 0.35 T in 2 millisecond. The average induced emf in the coil is
A) 1.77 V
B) 17.7 V
C) 177 V
D) 0.177 V
Explanation
(b) Induced emf$\ e = \frac{- NA\left( B_{2} - B_{1} \right)\cos\theta}{\mathrm{\Delta}t}$
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ = \ \frac{50 \times \pi \times \left( 3 \times 10^{- 2} \right)^{2}\lbrack 0.35 - 0.10\rbrack\cos{0{^\circ}}}{2 \times 10^{- 3}}$
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ = 17.7\ V$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.