Test: Growth in an Inductive Circuit - Electrical Engineering (EE) MCQ

Inductance is inversely proportional to current since, as the inductance increases, current decreases.

In a pure inductive circuit, current is lagging by 90 degrees from the voltage. The power factor is the cosine of the angle in between the voltage and the current. If the angle between the voltage and current is 90, then cos90=0. Hence, the power factor is zero.

The formula for magnetic field strength in a coil is:
H=iN/l
The inductance is: directly proportional to magnetic field strength, hence as the current value dou-bles, the inductance also doubles.

The average emf induced is proportional to the current per unit time, the constant of proportionality being L. Hence emf=LI/t. Making L the subject of the formula, we get: L=emf*t/I.

The correct formula for growth in an inductive circuit is VL=V(1-e^-t /time constant). As the time increases, the current in the inductor increases hence the voltage also increases.

We know that: V=V0(1-e^-t /time constant).
When time constant=t, we have: V=V0(1-e^-1)= 0.63*V0.
Hence the time constant is the time taken for the charge in an inductive circuit to become 0.63 times its initial charge.

The time constant in an inductive circuit is the time taken for the voltage across the inductor to become 63 percent of its initial value. It is given by: Time constant= L/R.

We know that: Time constant= L/R
Substituting the values from the given question, we get time constant= 2s.

We know that: Time constant= L/R
Substituting the values from the given question, we get R=5ohm.

 We know that: Time constant= L/R
Substituting the values from the given question, we get L=10H.