Question

Figure shows a square loop of resistance $1\Omega$ of side $1m$ being moved towards right at a constant speed of $1m/s$. The front edge enters the $3m$ wide magnetic field $(B=1T)$ at $t=0$. Draw the graph of current induced in the loop as time passes. (Take anticlockwise direction of current as positive)

Answer 1

From $t=0$ to $t=1s$ front edge enters magnetic field, flux through coil increases and is given by from zero to $(1\times 1\times 1)$ or from zero to $1Wb$

From $t=1s$ to $t=3s$ square loop remains inside the magnetic field, and hence flux remains constant $=1Wb$ from $t=1s$ to $t=3s$.

From $t=3s$ to $t=4s$ square loop comes out of the magnetic field, and hence flux be from $1Wb$ to $0Wb$. Current will be anti-clockwise from $t=1s$ to $t=3s$.

$E=-\frac{d\varphi }{dt}=$ Slope of the line $=1Volt$

$I=\frac{E}{R}=\frac{1Volt}{1\Omega }=1A$