A circular loop of radius 7 cm is placed in uniform magnetic field of 0.2 T directed perpendicular to plane of loop. The loop is converted into a square loop in 0.5 s. The EMF induced in the loop is _ _ _ _ mV.

Step-by-step solution

Circular loop with radius r = 0.07 m in magnetic field B = 0.2 T. Initial flux through circular loop: ₁ = B r^2 = 0.2 (0.07)^2 = 0.000980 Wb The loop is converted to a square maintaining the same perimeter: C = 2 r = 0.14 m Side of square: a = 0.14 4 = 0.035 m Final flux through square loop: ₂ = B a^2 = 0.2 (0.035 )^2 = 0.2 0.001225 ^2 Wb Evaluating: ₁ = 0.2 0.0154 = 0.00308 Wb ₂ = 0.2 0.001225 9.87 = 0.00242 Wb Change in flux: = 0.00308 - 0.00242 = 0.00066 Wb Average EMF: = t = 0.00066 0.5 = 0.00132 V = 1.32 mV