Question

A coil having $100$ turns and area of $0.001m^2$ is free to rotate about an axis passing through a diameter. The coil is placed perpendicular to a magnetic field of $1Wb/m^2$. If the coil is rotated rapidly through an angle of ${180}^{\circ }$. The resistance of the coil is $100\Omega$. The charge flown through coil is $2\times {10}^{-x}$ coulombs. Find $x$

Answer 1

Charge flown=$\int Idt=\int \frac{-d\varphi /dt}{R}dt$

Magnitude of flown charge=$\frac{\Delta \varphi }{R}=\frac{2NBA}{R}=2\times {10}^{-3}C$