1. What is the inductive reactance of an inductor of inductance L connected to an alternating current of angular frequency ω?
A.
ωL
B.
L/ω
C.
ω/L
D.
1/(ωL)
Correct Answer:
ωL
Explanation:
The inductive reactance is given by X_L = ωL, where ω is the angular frequency and L is the inductance.
2. Which is the SI unit of inductive reactance?
A.
Henry
B.
Ohm
C.
Farad
D.
Tesla
Correct Answer:
Ohm
Explanation:
Inductive reactance opposes the flow of alternating current and, like resistance, is measured in ohms.
3. The inductive reactance of a coil connected to an AC source is directly proportional to its:
A.
Capacitance
B.
Resistance only
C.
Inductance and frequency
D.
Charge only
Correct Answer:
Inductance and frequency
Explanation:
Since X_L = 2πfL, inductive reactance is directly proportional to both the inductance L and frequency f.
4. What happens to the inductive reactance of a coil if the frequency of the AC supply is doubled?
A.
It becomes half
B.
It remains unchanged
C.
It becomes four times
D.
It becomes double
Correct Answer:
It becomes double
Explanation:
Inductive reactance is X_L = 2πfL. Therefore, doubling the frequency doubles the inductive reactance when inductance remains constant.
5. An inductor of inductance 1 H is connected to an AC source of frequency 1/(2π) Hz. What is its inductive reactance?
A.
0.5 Ω
B.
1 Ω
C.
2π Ω
D.
π Ω
Correct Answer:
1 Ω
Explanation:
Using X_L = 2πfL, X_L = 2π × 1/(2π) × 1 = 1 Ω.
6. If the inductance of a coil is increased while the AC frequency remains constant, its inductive reactance:
A.
Decreases
B.
Increases
C.
Becomes zero
D.
Remains constant
Correct Answer:
Increases
Explanation:
From X_L = 2πfL, inductive reactance increases directly with inductance when frequency is constant.
7. For an ideal inductor connected to an AC source, the current amplitude is related to the voltage amplitude by:
A.
I = VX_L
B.
I = X_L/V
C.
I = V/X_L
D.
I = V + X_L
Correct Answer:
I = V/X_L
Explanation:
For an ideal inductive circuit, the magnitude of current is I = V/X_L, where X_L is the inductive reactance.
8. An inductor has inductive reactance 10 Ω at a certain frequency. If its inductance is halved at the same frequency, its new inductive reactance is:
A.
5 Ω
B.
10 Ω
C.
15 Ω
D.
20 Ω
Correct Answer:
5 Ω
Explanation:
Inductive reactance is directly proportional to inductance. Halving the inductance therefore halves the reactance from 10 Ω to 5 Ω.
9. The inductive reactance of a coil is zero when the frequency of the alternating current is:
A.
Zero
B.
Very high
C.
Equal to the inductance
D.
Equal to the resistance
Correct Answer:
Zero
Explanation:
Since X_L = 2πfL, the inductive reactance becomes zero when the frequency f is zero.
10. A coil of inductance 0.5 H is connected to an AC source of frequency 10 Hz. Taking π = 3.14, its inductive reactance is approximately:
A.
15.7 Ω
B.
31.4 Ω
C.
5 Ω
D.
62.8 Ω
Correct Answer:
31.4 Ω
Explanation:
Using X_L = 2πfL, X_L = 2 × 3.14 × 10 × 0.5 = 31.4 Ω.
Short questions are currently unavailable for this page.