1. What is the SI unit of magnetic flux?
A.
Tesla
B.
Weber
C.
Henry
D.
Volt
Correct Answer:
Weber
Explanation:
The SI unit of magnetic flux is the weber (Wb).
2. Magnetic flux through a plane surface is given by which expression for a uniform magnetic field?
A.
BA sin θ
B.
B/A
C.
BA cos θ
D.
B + A
Correct Answer:
BA cos θ
Explanation:
Magnetic flux is Φ = BA cos θ, where θ is the angle between the magnetic field and the normal to the surface.
3. A surface of area A is placed in a uniform magnetic field B. The magnetic flux is maximum when the field is parallel to the:
A.
Surface
B.
Normal to the surface
C.
Edge of the surface only
D.
Direction perpendicular to the normal
Correct Answer:
Normal to the surface
Explanation:
Flux Φ = BA cos θ is maximum when θ = 0°, meaning the magnetic field is parallel to the surface normal.
4. The magnetic flux through a surface is zero when the magnetic field is:
A.
Parallel to the normal of the surface
B.
Perpendicular to the surface
C.
Parallel to the surface
D.
Equal to the area of the surface
Correct Answer:
Parallel to the surface
Explanation:
When the magnetic field is parallel to the surface, it is perpendicular to the normal, so θ = 90° and Φ = BA cos 90° = 0.
5. A magnetic field of 2 T passes normally through a surface of area 3 m². What is the magnetic flux through the surface?
A.
1.5 Wb
B.
5 Wb
C.
6 Wb
D.
9 Wb
Correct Answer:
6 Wb
Explanation:
Since the field is normal to the surface, Φ = BA = 2 × 3 = 6 Wb.
6. Which quantity determines the magnetic flux through a surface in a uniform magnetic field?
A.
Magnetic field, area, and orientation of the surface
B.
Only the mass of the surface
C.
Only the temperature of the surface
D.
Only the resistance of the surface
Correct Answer:
Magnetic field, area, and orientation of the surface
Explanation:
Magnetic flux depends on the field strength, the surface area, and the angle between the field and the surface normal.
7. If the area of a surface is doubled while the magnetic field and orientation remain unchanged, the magnetic flux becomes:
A.
Half
B.
Unchanged
C.
Doubled
D.
Zero
Correct Answer:
Doubled
Explanation:
From Φ = BA cos θ, doubling A doubles the magnetic flux when B and θ remain constant.
8. If the magnetic field through a fixed surface is doubled without changing its orientation, the magnetic flux becomes:
A.
Half
B.
Doubled
C.
Unchanged
D.
One-fourth
Correct Answer:
Doubled
Explanation:
Magnetic flux is directly proportional to the magnetic field strength, as shown by Φ = BA cos θ.
9. For a magnetic field of 4 T and a surface area of 2 m², the maximum magnetic flux is:
A.
2 Wb
B.
4 Wb
C.
6 Wb
D.
8 Wb
Correct Answer:
8 Wb
Explanation:
Maximum flux occurs when the field is normal to the surface, so Φmax = BA = 4 × 2 = 8 Wb.
10. Magnetic flux is a measure of the magnetic field passing through a:
A.
Point charge
B.
Surface
C.
Resistor only
D.
Wire length only
Correct Answer:
Surface
Explanation:
Magnetic flux represents the amount of magnetic field passing through a specified surface.
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