Test: Current & Voltage in an Inductive Circuit, Capacitive Circuit - Electrical Engineering (EE) MCQ

The inductor does not allow sudden changes in current because if current changes in the inductor occur in zero time, the voltage becomes zero which is not possible.

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

The 1 ohm, 2 ohm and 3 ohm resistors are connected in parallel. Its equivalent resistance is in series with the 4 ohm resistor and the parallel connection of the 5 ohm and 6 ohm resistor. The equivalent resistance of this combination is 80/11 ohm. This is in parallel with 7 ohm to give equivalent resistance between A and B is 3.56 ohm.

The circuit which contains only inductance (L) and not any other quantities like resistance and capacitance in the circuit is called a Pure inductive circuit. In this type of circuit, the current lags behind the voltage by an angle of 90 degrees.

Any circuit in which a change of current is accompanied by a change of flux, and therefore by an induced emf, is said to be inductive.

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 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 average emf induced in a coil is L=NΦ/t.

The average current is the average of the current which flows in the inductor. Hence it is I/2.

Average current= I/2.
Substituting the value of I from the equation, average current= 13A.

The capacitive reactance decreases as the frequency increases since they are in-versely proportional. The voltage is directly proportional to the capacitive reactance, hence it de-creases.

When voltage across a capacitor increases, the charge stored in it also increases be-cause charge is directly proportional to voltage, capacitance being the constant of proportionality.

When a capacitor is fully charged, it does not store any more charge.There is no change in charge with time. Current is the rate of change of charge, hence it becomes zero, or stops.

The capacitive reactance Xc is the reciprocal of the product of the angular velocity and the capacitance. The angular velocity=2*pi*f, therefore Xc=1/(2*f*pi*C).

Q is directly proportional to V. The constant of proportionality in this case is C, that is, the capacitance. Hence C=Q/V.
C=80microC/4V=20microF.

 The capacitive reactance decreases as the frequency increases since they are in-versely proportional. The current is inversely proportional to the capacitive reactance, hence it in-creases.

Q is directly proportional to V. The constant of proportionality in this case is C, that is, the capacitance. Hence Q=CV.
Q=3*2=6C.
I=Q/t= 6/2=3A.

 Q is directly proportional to V. The constant of proportionality in this case is C, that is, the capacitance. Hence Q=CV.
Q=3*2=6C.

We know that: Xc=1/(2*f*pi*C).
Substituting the values from the given question, we get Xc= 106.2 ohm.

We know that: Xc=1/(2*f*pi*C).
Substituting the values from the given question, we get Xc= 106.2 ohm.
I=V/Xc, hence I= 3.77A.