Question

A coil having an area of $2m^2$ is placed in a magnetic field which changes from $1Weber/m^2$ to $4Weber/m^2$ in $2$ seconds. The e.m.f. induced in the coil will be

• A. $4volt$
• B. $3volt$
• C. $2volt$
• D. $1volt$

Answer 1

The correct option is B $3volt$

Given,

Change in Magnetic field, $\Delta B=(4weber/m^2-1weber/m^2)=3weber/m^2$

Time difference, $\Delta t=2\sec$

Area of coil, $A=2m^2$

$\epsilon =-\frac{\Delta \varphi }{\Delta t}=\frac{A\Delta B}{\Delta t}$

$\epsilon =-\frac{2\times 3}{2}=-3Volt$

(-ve sign, is just to show direction emf)

E.m.f generate is $3Volt$