• # question_answer A rectangular coil of 100 turns and size $0.1m\times 0.05\,m$ is placed perpendicular to amagnetic field of 0.1 T. The induced $emf$ when the field drops to 0.05 T is 0.05 s is A)  0.5V               B)  1.0V C)  1.5V               D)  2.0V

Area of the coil $\Rightarrow$ Change in magnetic field = 0.05 - 0.1 = -0.05T Therefore, change in flux is $M=(AL)d\,\,\,\Rightarrow \,\,\frac{M}{Ad}$ $\Rightarrow$ Induced emf for one turn $T=2\pi \,\,\sqrt{\frac{M}{2Adg}}$ $\Delta DBS,$ Induced emf for 100 turns (in magnitude)  $SD=\sqrt{{{60}^{2}}+{{25}^{2}}}$ $=\sqrt{4225}=65=DP$