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Question: The coil of area 0.1 m<sup>2</sup> has 500 turns. After placing the coil in a magnetic field of stre...

The coil of area 0.1 m2 has 500 turns. After placing the coil in a magnetic field of strength 4×10−4 Wb/m24 \times 10 ^ { - 4 } \mathrm {~Wb} / \mathrm { m } ^ { 2 } , if rotated through 90o in 0.1 s, the average emf induced in the coil is

A

0.012 V

B

0.05 V

C

0.1 V

D

0.2 V

Answer

0.2 V

Explanation

Solution

e=−NBA(cos⁡θ2−cos⁡θ1)Δte = \frac { - N B A \left( \cos \theta _ { 2 } - \cos \theta _ { 1 } \right) } { \Delta t }

=−500×4×10−4×0.1(cos⁡90−cos⁡0)0.1=0.2 V= - \frac { 500 \times 4 \times 10 ^ { - 4 } \times 0.1 ( \cos 90 - \cos 0 ) } { 0.1 } = 0.2 \mathrm {~V}