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.
2. Inductance is __________ to number of turns in the coil.
A. directly proportional
B. inversely proportional
C. equal
D. not related
Answer: A
L = µ0N2A/l
Inductance is directly proportional to the number of turns in the coil.
3. Choke involve use of _____________
A. Resistor
B. Capacitor
C. Inductor
D. Transistor
Answer: C
Choke is a type of coil so it involves the use of an inductor. Capacitors cannot be used in choke coil.
4. What is the value of current in an inductive circuit when there is no applied voltage?
A. Minimum
B. Maximum
C. Zero
D. Cannot be determined
Answer: B
The current in an inductive circuit is maximum when there is no voltage applied because of the coils of the inductor store electric flux.
5. What is the current in an inductive circuit when the applied voltage is maximum?
A. Infinity
B. Maximum
C. Zero
D. Cannot be determined
Answer: C
The current in an inductive circuit is zero or minimum when the value of the applied voltage is maximum.
6. In an inductive circuit, the voltage_______ the current?
A. Leads
B. Lags
C. Is greater than
D. Is less than
Answer: A
In a pure inductive circuit, the voltage leads the current and the current lags the voltage by a phase difference of 90 degrees.
7. In an inductive circuit, the current________ the voltage?
A. Leads
B. Lags
C. Is greater than
D. Is less than
Answer: B
In a pure inductive circuit, the voltage leads the current, and the current lags the voltage by a phase difference of 90 degrees.
8. In which device inductor cannot be used?
A. filter circuit
B. transformer
C. choke
D. dielectric
Answer: D
Inductor has a wide number of applications.
It is used in LR filter circuits, transformers, and choke coils.
9. A resistance of 7 ohms is connected in series with an inductance of 31.8mH. The circuit is connected to a 100V 50Hz sinusoidal supply. Calculate the current in the circuit.
A. 2.2A
B. 4.2A
C. 6.2A
D. 8.2A
Answer: D
XL = 2 × π × f × L = 10 ohm.
Impedance is given by
Z2 = (R2+XL2)
Therefore the total impedance Z = 12.2ohm.
V = IZ
∴ I = V/Z
= 100/12.2 = 8.2A.
10. A resistance of 7 ohms is connected in series with an inductance of 31.8mH. The circuit is connected to a 100V 50Hz sinusoidal supply. Calculate the phase difference.
A. -55.1
B. 55.1
C. 66.1
D. -66.1
Answer: A
The phase angle of the Inductive circuit is given as
φ = tan-1(XL/R) = 55.1
Since this is an inductive circuit, the current will lag, hence φ = -55.1.
