Question

A coil having $200$ turns has a surface area of $0.15m^2$. A magnetic field of strength $0.2$T applied perpendicular to this changes to $0.6$T in $0.4$s, then the induced emf in the coil is ________V.

• A. $45$
• B. $30$
• C. $15$
• D. $60$

Answer 1

The correct option is B $30$

Number of turns $N=200$
Area of coil $A=0.15m^2$
Rate of change of magnetic field $\frac{\Delta B}{\Delta t}=\frac{0.6-0.2}{0.4}=1T/s$
Induced emf $E=NA\frac{\Delta B}{\Delta t}$
$⟹E=200\times 0.15\times 1=30V$
Correct answer is option B.