Question

In a magnetic field of $0.05T$ area of coil changes from $101c{m}^2$ to $100c{m}^2$ 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 $2.5\times {10}^{-6}C$

$B=0.5T$
$A_1=101c{m}^2=101\times {10}^{-4}{m}^2$
$A_2=100c{m}^2=100\times {10}^{-4}{m}^2$
$R=2\Omega$
Amount of charge
$q=\frac{B\Delta A}{R}$
$=\frac{0.50\times (101\times {10}^{-4}-100\times {10}^{-4})}{2}$
$=\frac{0.5\times 1\times {10}^{-4}}{2}$
$=2.5\times {10}^{-6}C$