Answer:
Step-by-step 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 .