Question

A coil of area 500 cm² and having 1000 turns is held perpendicular to a uniform magnetic field of 0.4 gauss. The coil is turned through 180° in 1/10 second. The average induced emf (in volt) is ________.

Answer 1

Here, A = 500 cm² = 500 x 10^-4 m² 

N = 1000, B = 0.4 G = 0.4 x 10^-4 T 

t = 1/10 s

When the coil is held perpendicular to the field, the normal to the plane of the coil makes an angle of 0° with the field B. 

Initially, flux, ϕ₁ = BA cos0° = BA 

Finally, flux, ϕ₂ = BA cos180° = –BA