Question

For an inductor in a DC circuit involving a switch that can be opened or closed, the the induced emfs in the inductor....

A) keep the current in the inductor the same as it was before the switch was opened/closed.

B) keep the voltage across the inductor the same as it was before the switch was opened/closed.

C) make sure that the current through the inductor is immediately zero if the switch is opened, and immediately not zero if the switch was closed.

D) make sure that the voltage across the inductor is always zero.

Answer 1

Solution:

Answer:A) keep the current in the inductor the same as it was before the switch was opened/closed.

Inductor stores the energy in a magnetic field and tries to maintain a constant current through its windings.

Current thru the inductor is stable I_L = V/R , where R is the load resistance in the circuit. ; but V_L = 0 , since there is no induced EMF across it .

When the Inductor is disconnected from the power supply, the I_L does not change in magnitude or direction

but V_L reverses polarity and drops from 0 to a negative value.

As the energy decays thru R , the V_L once again returns to 0 and IL starts decreasing and drops to 0 .