A 139-turn circular coil of radius 2.13 cm is immersed in a uniform magnetic field that is perpendicular to the plane of the coil. during 0.175 s the magnetic field strength increases from 57.7 mt to 92.1 mt. find the magnitude of the average emf, in millivolts, that is induced in the coil during this time interval.

Explanation:

Change in magnetic flux = no of turns x area of coil  x change in magnetic field .

= 139 x π R² x ( 92.1 - 57.7 ) x 10⁻³

= 139 x 3.14 x 2.13²X 10⁻⁴ x 34.4 x 10⁻³

= 6.8118 x 10⁻³ Weber

rate of change of flux = change of flux / time

= 6.8118 x 10⁻³ / .175

= 38.925 mV .

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