Question 272: Electromagnetic Induction

Question

A coil having effective area A, is held with its plane normal to magnetic field of induction B. The magnetic induction is quickly reduced by $$25 \%$$ of its initial value in 2 second. Then the e.m.f. induced across the coil will be

Accepted Answer

The induced emf is given as
$$\mathrm{e}=\frac{\Delta \phi}{\Delta \mathrm{t}}=\frac{\mathrm{A} 	riangle \mathrm{B}}{\Delta \mathrm{t}}$$
The magnetic field is reduced by $$25 \%$$ of its initial value.
The final magnetic field is,
$$\begin{aligned}
& \mathrm{B}_2=\mathrm{B}-\frac{1}{4} \mathrm{~B}=\frac{3}{4} \mathrm{~B} \\
	herefore \quad & \mathrm{e}=\frac{\mathrm{A}\left(\mathrm{B}-\frac{3}{4} \mathrm{~B}ight)}{2}=\frac{\mathrm{AB}}{8}
\end{aligned}$$

Answer

$$\frac{\mathrm{AB}}{8}$$

Answer

$$\frac{\mathrm{AB}}{2}$$

Answer

$$\frac{3 \mathrm{AB}}{4}$$

Answer

$$\frac{3 \mathrm{AB}}{8}$$

Electromagnetic Induction

A coil having effective area A, is held with its plane normal to magnetic field of induction B. The magnetic induction is quickly reduced by $25 \%$ of its initial value in 2 second. Then the e.m.f. induced across the coil will be

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