Question

In a magnetic field of $0.05T$ 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. $10\times {10}^{-6}C$
• D. $8\times {10}^{-6}C$

Answer 1

The correct option is A $2.5\times {10}^{-6}C$

Given : $B=0.5$ T $R=2\Omega$

Change in area of coil $\Delta A=101-1001$ $c{m}^2={10}^{-4}$ $m^2$

Thus change in flux $\Delta \varphi =B\Delta A=0.05\times {10}^{-4}=5\times {10}^{-6}$ Wb

Charge flowing $q=\frac{\Delta \varphi }{R}$

$\therefore$ $q=\frac{5\times {10}^{-6}}{2}=2.5\times {10}^{-6}$ $C$