1. Flux linkage of a coil is defined as:
A.
The magnetic flux through one turn only
B.
The product of the number of turns and magnetic flux through each turn
C.
The magnetic field divided by the number of turns
D.
The resistance multiplied by the magnetic flux
Correct Answer:
The product of the number of turns and magnetic flux through each turn
Explanation:
Flux linkage is given by NΦ, where N is the number of turns and Φ is the magnetic flux through each turn.
2. A coil has 20 turns, and the magnetic flux through each turn is 0.5 Wb. What is the flux linkage?
A.
0.025 Wb-turn
B.
10 Wb-turn
C.
20.5 Wb-turn
D.
40 Wb-turn
Correct Answer:
10 Wb-turn
Explanation:
Flux linkage = NΦ = 20 × 0.5 = 10 Wb-turn.
3. If the number of turns in a coil is doubled while the flux through each turn remains constant, the flux linkage becomes:
A.
Half its original value
B.
Unchanged
C.
Twice its original value
D.
Four times its original value
Correct Answer:
Twice its original value
Explanation:
Since flux linkage is NΦ, doubling N doubles the flux linkage when Φ is constant.
4. A single-turn loop has a magnetic flux of 0.08 Wb through it. Its flux linkage is:
A.
0.008 Wb-turn
B.
0.08 Wb-turn
C.
0.8 Wb-turn
D.
8 Wb-turn
Correct Answer:
0.08 Wb-turn
Explanation:
For one turn, N = 1, so flux linkage NΦ = 1 × 0.08 = 0.08 Wb-turn.
5. A 50-turn coil has a flux linkage of 2 Wb-turn. What is the magnetic flux through each turn?
A.
0.004 Wb
B.
0.04 Wb
C.
25 Wb
D.
100 Wb
Correct Answer:
0.04 Wb
Explanation:
Using NΦ = 2, the flux through each turn is Φ = 2/50 = 0.04 Wb.
6. For a coil with identical magnetic flux through every turn, flux linkage increases when:
A.
The number of turns decreases
B.
The flux through each turn decreases
C.
The number of turns increases
D.
The coil is removed from the magnetic field
Correct Answer:
The number of turns increases
Explanation:
Flux linkage is NΦ, so increasing the number of turns increases the total flux linkage if the flux per turn is unchanged.
7. A 100-turn coil is linked by a flux of 3 × 10^-3 Wb per turn. Its flux linkage is:
A.
3 × 10^-5 Wb-turn
B.
3 × 10^-3 Wb-turn
C.
0.3 Wb-turn
D.
3 Wb-turn
Correct Answer:
0.3 Wb-turn
Explanation:
Flux linkage = NΦ = 100 × 3 × 10^-3 = 0.3 Wb-turn.
8. If the magnetic flux through each turn of a coil becomes zero, its flux linkage is:
A.
Zero
B.
Equal to the number of turns
C.
Equal to the area of the coil
D.
Infinite
Correct Answer:
Zero
Explanation:
Since flux linkage is NΦ, a zero flux through each turn gives zero flux linkage.
9. The flux linkage of a coil depends directly on:
A.
The number of turns and the magnetic flux per turn
B.
The resistance and length of the wire
C.
The mass and volume of the coil
D.
The temperature and density of the wire
Correct Answer:
The number of turns and the magnetic flux per turn
Explanation:
The relation for flux linkage is NΦ, showing direct dependence on both the number of turns and the flux through each turn.
10. A coil has 25 turns and a flux linkage of 5 Wb-turn. The magnetic flux through each turn is:
A.
0.02 Wb
B.
0.2 Wb
C.
5 Wb
D.
125 Wb
Correct Answer:
0.2 Wb
Explanation:
Using NΦ = 5, the flux per turn is Φ = 5/25 = 0.2 Wb.
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