Faraday's Law Of Induction

Faraday's law of electromagnetic induction states that the EMF induced in a closed loop equals the negative time rate of change of magnetic flux (\Phi = BA) linking that loop. For a stationary loop of fixed area lying perpendicular to a changing field, only the field magnitude varies, so the flux change is governed entirely by (\Delta B). The average induced EMF is (|\varepsilon| = A,\dfrac{\Delta B}{\Delta t}). Substituting (A = 0.02) m^2, (\Delta B = 0.5 - 0.1 = 0.4) T and (\Delta t = 0.2) s gives (|\varepsilon| = 0.02 \times 0.4/0.2 = 0.04) V. The option 0.02 V is wrong because it uses only half the field change. The option 0.08 V incorrectly doubles the area contribution. The option 0.20 V mistakenly drops the area factor and uses (\Delta B/\Delta t) alone. This is the standard NCERT formulation of motional flux change in a fixed coil. A plausibility check confirms the unit T·m^2/s equals the volt, and the magnitude is reasonable for such a slow, weak-field variation.