MHTCET 20 Apr 2026 Shift 1 Paper

Concept:Faraday's law of electromagnetic induction relates the induced e.m.f. to the rate of change of magnetic flux through the coil.Explanation:Initial magnetic field,$$B_i = 0.05\ \mathrm{Wb\,m^{-2}}$$Final magnetic field is 20% of the initial value,$$B_f = \frac{20}{100} \times 0.05 = 0.01\ \mathrm{Wb\,m^{-2}}$$Change in magnetic field,$$\Delta B = B_i - B_f = 0.05 - 0.01 = 0.04\ \mathrm{Wb\,m^{-2}}$$The coil is perpendicular to the field, so the effective area is used directly.Induced e.m.f.,$$E = \frac{A_{\text{eff}} \Delta B}{\Delta t} = \frac{3 \times 0.04}{10} = 0.012\ \mathrm{V}$$Converting to millivolts,$$E = 0.012 \times 1000 = 12\ \mathrm{mV}$$Answer:The induced e.m.f. in the coil is $12\ \mathrm{mV}$.Therefore, the correct option is B. 12 mV.