171k views
3 votes
When the 20.0 A current through an inductor is turned off in 1.50 ms, an 800 V emf is induced, opposing the change. What is the value of the self-inductance?

a) 0.040 H
b) 0.053 H
c) 0.067 H
d) 0.080 H

1 Answer

4 votes

Final answer:

To calculate the self-inductance (L) of an inductor, the formula L = -e / (dI/dt) is used. When an induced emf of 800 V is produced by a current change of 20.0 A over 1.50 ms, the self-inductance is found to be 0.060 H, not matching the options given in the question.

Step-by-step explanation:

The student wants to find the self-inductance of an inductor. This is a concept from physics, specifically electromagnetism. The induced electromotive force (emf) can be calculated using Faraday's law of induction, which states that the induced emf in a coil is equal to the negative change in magnetic flux over time. In the case of self-inductance, the formula is e = -L(dI/dt), where e is the induced emf, L is the self-inductance, and dI/dt is the rate of change of current. Given that the induced emf is 800 V when the current change is 20.0 A over a time of 1.50 ms, we can rearrange the formula to solve for L:

L = -e / (dI/dt)

Inserting the given values, we get:

L = -800 V / (20.0 A / 1.50 x 10-3 s)

L = -800 V / (13333.33 A/s)

L = 0.060 H

However, since inductance cannot be negative, we take the absolute value of the result:

L = 0.060 H

Therefore, the correct answer is 0.060 H, which is not listed in the options provided. There may be a mistake in the options or in the data provided in the question.

User Aonan Zhang
by
7.6k points