placement online test 5

1. 1. What does magnetic permeability represent?

• A) Resistance to magnetic flux

• B) Ability of a material to retain magnetism

• C) Ability of a material to support magnetic flux

• D) Opposition to electric current

Answer explanation

C) Ability of a material to support magnetic flux

Explanation:

Magnetic permeability (μ) is a measure of how easily a material allows magnetic lines of force (flux) to pass through it. Materials with high permeability (like iron) support strong magnetic flux.

2. Which quantity is analogous to current in a magnetic circuit?

• A) Magnetic flux

• B) Magnetic reluctance

• C) Magnetic field strength

• D) Magnetic permeability

Answer explanation

A) Magnetic flux

Explanation:

In the magnetic circuit analogy:

Magnetic flux (Φ) is analogous to electric current (I),

MMF (magnetomotive force) is like voltage (V),

Reluctance (R) is like resistance.

3. The magnetic flux in a core is 0.005 Wb and the area of cross-section is 0.001 m². What is the flux density?

• A) 0.005 T

• B) 5 T

• C) 0.5 T

• D) 50 T

Answer explanation

B) 5 T

Explanation:

Flux Density

4. Which of the following is not a property of magnetic lines of force?

• A) They form closed loops

• B) They intersect each other

• C) They travel from North to South outside a magnet

• D) They never cross each other

Answer explanation

B) They intersect each other

Explanation:

Magnetic lines of force never intersect because each point in space has a unique direction of magnetic field. So, this statement is false and is the correct answer.

5. The MMF of a coil with 250 turns carrying 2 A current is:

• A) 125 A-turns

• B) 250 A-turns

• C) 750 A-turns

• D) 500 A-turns

Answer explanation

D) 500 A-turns

Explanation:

MMF = Number of turns (N) × Current (I)

MMF = 250 × 2 = 500 A-turns