Practice Test: Question Set - 03
1. Main causes of noisy solenoid are
- (A) Strong tendency of fan out of laminations at the
end caused by repulsion among magnetic lines of force
- (B) Uneven bearing surface, caused by dirt or uneven
wear between moving and stationary parts
- (C) Both of above
- (D) None of the above
2. A basic one-loop dc generator is rotated at 90 rev/s. How many times each second does the dc output voltage peak (reach maximum)?
- (A) 90
- (B) 180
- (C) 270
- (D) 360
3. Paramagnetic materials have relative permeability
- (A) Slightly less than unity
- (B) Equal to unity
- (C) Slightly more than unity
- (D) Equal to that ferromagnetic mate rails
4. When the speed at which a conductor is moved through a magnetic field is increased, the induced voltage
- (A) Increases
- (B) Decreases
- (C) Remain
constant
- (D) Reaches zero
5. A relay is an electromagnetically controlled mechanical device in which electrical contacts are opened or closed by a magnetizing current.
- (A) True
- (B) False
6. The magnetism left in the iron after exciting field has been removed is known as
- (A) Permeance
- (B) Residual magnetism
- (C) Susceptance
- (D) Reluctance
7. When the north poles of two bar magnets are brought close together, there will be
- (A) No force
- (B) A downward
force
- (C) A force of
attraction
- (D) A force of
repulsion
8. Susceptibility is positive for
- (A) Nonmagnetic substances
- (B) Diamagnetic substances
- (C) Ferromagnetic substances
- (D) None of the above
9. If a loop in a basic dc generator suddenly begins rotating at a faster speed, the induced voltage
- (A) Remains
unchanged
- (B) Reverses
polarity
- (C) Increases
- (D) Decreases
10. The most effective and quickest may of making a magnet from soft iron is by
- (A) Placing it inside a coil carrying current
- (B) Induction
- (C) The use of permanent magnet
- (D) Rubbing with another magnet
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