Magnetism and Electromagnetism

MCQsQuestion.com has 29 Question/Answers about Topic Magnetism and Electromagnetism

After the magnetizing force has been removed, the ratio of the remaining magnetic flux to the saturated magnetic flux is called _____________.

After the magnetizing force has been removed, the ratio of the remaining magnetic flux to the saturated magnetic flux is called _____________.
  • A. saturation
  • B. retentivity
  • C. hysteresis
  • D. coercivity
  • Correct Answer: Option B

When the speed at which a conductor is moved through a magnetic field is increased, the induced voltage will _____.

When the speed at which a conductor is moved through a magnetic field is increased, the induced voltage will _____.
  • A. not be affected
  • B. equal 0 V
  • C. decrease
  • D. increase
  • Correct Answer: Option D

The induced voltage across a stationary conductor in a stationary magnetic field ___.

The induced voltage across a stationary conductor in a stationary magnetic field ___.
  • A. equals 0 V
  • B. is usually very large
  • C. varies with time
  • D. depends on the strength of the magnetic field
  • Correct Answer: Option A

The ___ is an electromagnetic device that contains a coil rotating on a jeweled bearing mount.

The ___ is an electromagnetic device that contains a coil rotating on a jeweled bearing mount.
  • A. permanent-magnet speaker
  • B. d'Arsonval movement
  • C. single-pole, double-throw relay
  • D. crankshaft position sensor
  • Correct Answer: Option B

You can determine the direction of the lines of force surrounding a conductor by using _____.

You can determine the direction of the lines of force surrounding a conductor by using _____.
  • A. the right-hand rule
  • B. the left-hand rule
  • C. Lenz's law
  • D. Faraday's law
  • Correct Answer: Option A

A group of force lines going from the north pole to the south pole of a magnet is called the magnetic ___.

A group of force lines going from the north pole to the south pole of a magnet is called the magnetic ___.
  • A. retentivity
  • B. reluctance
  • C. hysteresis
  • D. flux
  • Correct Answer: Option D

Ferromagnetic materials have minute magnetic ___ created within their atomic structure by the orbital motion and spin of electrons.

Ferromagnetic materials have minute magnetic ___ created within their atomic structure by the orbital motion and spin of electrons.
  • A. forces
  • B. flux lines
  • C. domains
  • D. tapes
  • Correct Answer: Option C

___ is the ability of a material to remain magnetized after removal of the magnetizing force.

___ is the ability of a material to remain magnetized after removal of the magnetizing force.
  • A. Reluctance
  • B. Hysteresis
  • C. Retentivity
  • D. Induction
  • Correct Answer: Option C

The movable part in a relay is the _____.

The movable part in a relay is the _____.
  • A. plunger
  • B. armature
  • C. cone
  • D. brushes
  • Correct Answer: Option B

The flux density is ___ when the magnetic flux is 9 µWb and the cross-sectional area of the magnetic field is 5 × 10–3 m2.

The flux density is ___ when the magnetic flux is 9 µWb and the cross-sectional area of the magnetic field is 5 × 10–3 m2.
  • A. 1800 µT
  • B. 555.56 T
  • C. 9 µT
  • D. 5 × 10–3 T
  • Correct Answer: Option A

When the current through a coil reverses direction, the magnetic field around the coil _____.

When the current through a coil reverses direction, the magnetic field around the coil _____.
  • A. does not change
  • B. disappears
  • C. increases in strength
  • D. reverses direction
  • Correct Answer: Option D

“Series” and “parallel” as applied to dc motors refer to

“Series” and “parallel” as applied to dc motors refer to
  • A. the connection of the motor and controller
  • B. the connection of the field coil and armature windings
  • C. the connection of the brush and commutator
  • D. the connection of the motor batteries
  • Correct Answer: Option B

The component that produces power in an electromagnetic generator is called the

The component that produces power in an electromagnetic generator is called the
  • A. armature
  • B. field winding
  • C. commutator
  • D. brush
  • Correct Answer: Option A

A Hall effect sensor

A Hall effect sensor
  • A. exists only in theory
  • B. is a noncontacting magnetic sensor
  • C. can operate only a few times before failure
  • D. produces very large voltages
  • Correct Answer: Option B

The Hall effect

The Hall effect
  • A. is a phenomenon with no practical applications
  • B. is used in various sensor applications
  • C. can develop potentials of thousands of volts
  • D. is the basis for solar cell operation
  • Correct Answer: Option B
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