Question

Calculate the induced emf in a coil of 1 mH inductance in which current changes from 0.1 A to 2.1 A in 0.01 s.
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Answer 1

Answer: -0.2 volts

Explanation: Induced emf = -Ldi/dt

=1mH x (2.1-0.1)/0.01 = -0.2 volts

Answer 2

Explanation:

Rate of change of current

dt

di

=

0.1

0.0−2.5

⟹

dt

di

=−25 A/s

Induced emf E=200V

Using E=−L

dt

di

∴ 200=−L×(−25)

⟹ L=8H

Answer By