Q. In a magnetic field of $0.05T$, area of a coil changes from $101cm^{2}$ to $100cm^{2}$ without changing the resistance which is $2\Omega$. The amount of charge that flow during this period is
A) $2.5 \times 10^{- 6}\ coulomb$
B) $2 \times 10^{- 6}\ coulomb$
C) $10^{- 6}\ coulomb$
D) $8 \times 10^{- 6}\ coulomb$
Explanation
(a) $\phi = BA$
$\Rightarrow$ change in flux $d\phi = BdA = 0.05(101 - 100)10^{- 4}$
$= 5 \times 10^{- 6}Wb$
Now, charge $dQ = \frac{d\phi}{R} = \frac{5 \times 10^{- 6}}{2} = 2.5 \times 10^{- 6}C$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.