Question

In a magnetic field of $0.05\, T$ area of coil changes from $101 cm ^{2}$ to $100 \,cm ^{2}$ without changing the resistance which is $2 \,\Omega$. The amount of charge that flow during this period is

• A. $2.5 \times 10^{-6} C$
• B. $2 \times 10^{-6} C$
• C. $10^{-6} C$
• D. $8 \times 10^{-6} C$

Answer 1

The Correct Option is A

Given, $B=0.5 T$ $A_{1}=101\, cm ^{2}=101 \times 10^{-4}\, m ^{2}$ $A_{2}=100\, cm ^{2}=100 \times 10^{-4} \,m ^{2} $ $R=2 \Omega$ Amount of charge $q=\frac{B \Delta A}{R}$ $=\frac{0.05 \times\left(101 \times 10^{-4}-100 \times 10^{-4}\right)}{2} $ $=\frac{0.05 \times 1 \times 10^{-4}}{2}=2.5 \times 10^{-6} \,C$