Question 1

Faraday's law states that the:

Accepted Answer

A)  direction of induced voltage produces an opposition. 
B)  emf depends on the rate of cutting flux. 
C)  direction of an induced current produces an aiding effect. 
D)  emf is related to the direction of current. 
A)  direction of induced voltage produces an opposition. 
B)  emf depends on the rate of cutting flux. 
C)  direction of an induced current produces an aiding effect. 
D)  emf is related to the direction of current. B

Question 2

The B-H curve plots:

Accepted Answer

A)  flux intensity versus flux density 
B)  permeability versus reluctance. 
C)  retentivity versus saturation 
D)  flux density versus magnetizing force. 
A)  flux intensity versus flux density 
B)  permeability versus reluctance. 
C)  retentivity versus saturation 
D)  flux density versus magnetizing force. D

Question 3

Magnetomotive force in an electromagnet is increased by:

Accepted Answer

A)  increasing coil turns 
B)  decreasing the voltage 
C)  decreasing permeability 
D)  increasing coil length 
A)  increasing coil turns 
B)  decreasing the voltage 
C)  decreasing permeability 
D)  increasing coil length A

Question 4

The force between carrying current parallel conductors:

Accepted Answer

A)  is one of repulsion for the same direction of current flow. 
B)  is one of attraction for the same direction of current flow. 
C)  is cancelled no matter what the direction of current flow. 
D)  is neutral because the force fields from each conductor cancel each other out. 
A)  is one of repulsion for the same direction of current flow. 
B)  is one of attraction for the same direction of current flow. 
C)  is cancelled no matter what the direction of current flow. 
D)  is neutral because the force fields from each conductor cancel each other out.

Question 5

What is the amount of flux in an 8-turn coil with 1.5 A of current if the reluctance is .04 x 106 At/Wb?

Accepted Answer

A)  150 µWb 
B)  300 µWb 
C)  0.48 µWb 
D)  1.24 µWb 
A)  150 µWb 
B)  300 µWb 
C)  0.48 µWb 
D)  1.24 µWb

Question 6

The Greek symbol is used to indicate the of a material in relation to flux lines.

Accepted Answer

A)  µ, permeability 
B)  1, reluctance 
C)  fi, Webers 
D)  6, Gauss 
A)  µ, permeability 
B)  1, reluctance 
C)  fi, Webers 
D)  6, Gauss

Question 7

The right hand rule is used for current-carrying conductors using electron flow.

Accepted Answer

A) True 
 B)False

Question 8

Relative permeability of a magnetic material is a ratio of its:

Accepted Answer

A)  absolute permeability to that of a vacuum 
B)  field intensity to its field density. 
C)  flux lines to its ampere-turns 
D)  area to its field density. 
A)  absolute permeability to that of a vacuum 
B)  field intensity to its field density. 
C)  flux lines to its ampere-turns 
D)  area to its field density.

Question 9

What constitutes an electromagnet?

Accepted Answer

A)  a core material with high reluctance with a coil of wire around it 
B)  a core material that can be easily magnetized with a coil of wire around it 
C)  a permanent magnet with a coil around it 
D)  a permanent magnet 
A)  a core material with high reluctance with a coil of wire around it 
B)  a core material that can be easily magnetized with a coil of wire around it 
C)  a permanent magnet with a coil around it 
D)  a permanent magnet

Question 10

Reluctance varies:

Accepted Answer

A)  directly with its permeability 
B)  directly with its area. 
C)  inversely with its permeability 
D)  inversely with its length. 
A)  directly with its permeability 
B)  directly with its area. 
C)  inversely with its permeability 
D)  inversely with its length.

Question 11

The ease with which domains align and a magnetic field is established, in a given material, is called the material's:

Accepted Answer

A)  magnetomotive force 
B)  retentivity 
C)  permeability 
D)  reluctance 
A)  magnetomotive force 
B)  retentivity 
C)  permeability 
D)  reluctance

Question 12

The ability of a material to maintain a magnetized state without the presence of a magnetizing force is called:

Accepted Answer

A)  retentivity 
B)  permeability 
C)  residual magnetism 
D)  reluctance 
A)  retentivity 
B)  permeability 
C)  residual magnetism 
D)  reluctance

Question 13

An example of an electromagnetic device that also uses a permanent magnet is:

Accepted Answer

A)  the relay 
B)  a tape recording head 
C)  the solenoid 
D)  the loudspeaker 
E)  all of the above 
A)  the relay 
B)  a tape recording head 
C)  the solenoid 
D)  the loudspeaker 
E)  all of the above

Question 14

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

Accepted Answer

A)  electromagnetism 
B)  magnetic flux 
C)  force energy 
D)  permeability 
A)  electromagnetism 
B)  magnetic flux 
C)  force energy 
D)  permeability

Question 15

According to Faraday's law, if the rate of flux change quadruples, what happens to the induced voltage?

Accepted Answer

A)  It quadruples 
B)  It doubles. 
C)  It increases by a factor of eight 
D)  It halves. 
A)  It quadruples 
B)  It doubles. 
C)  It increases by a factor of eight 
D)  It halves.

Question 16

Calculate the induced voltage across a coil with 150 turns that is being cut by a magnetic field that is changing at a rate of 7 Wb/s.

Accepted Answer

A)  105 V 
B)  1050 V 
C)  1.05 V 
D)  10.5 V 
A)  105 V 
B)  1050 V 
C)  1.05 V 
D)  10.5 V

Question 17

There is 1.5 A of current through a coil consisting of 8 turns, what is the magnetomotive force mmF)?

Accepted Answer

A)  5.33 ampere-turns At) 
B)  9.5 ampere-turns At) 
C)  12 ampere-turns At) 
D)  6.5 ampere-turns At) 
A)  5.33 ampere-turns At) 
B)  9.5 ampere-turns At) 
C)  12 ampere-turns At) 
D)  6.5 ampere-turns At)

Question 18

A Tesla is equal to a meter per Weber.

Accepted Answer

A) True 
 B)False

Question 19

Another name for a hysteresis loop is:

Accepted Answer

A)  field intensity 
B)  magnetomotive force 
C)  the B-H curve 
D)  flux density 
A)  field intensity 
B)  magnetomotive force 
C)  the B-H curve 
D)  flux density

Question 20

Magnetomotive force is:

Accepted Answer

A)  directly proportional to the number of turns in the coil, and inversely proportional to the current through the coil. 
B)  directly proportional to the number of turns in the coil, and directly proportional to the current through the coil. 
C)  inversely proportional to the number of turns in the coil, and inversely proportional to the current through the coil. 
D)  inversely proportional to the number of turns in the coil, and directly proportional to the current through the coil. 
A)  directly proportional to the number of turns in the coil, and inversely proportional to the current through the coil. 
B)  directly proportional to the number of turns in the coil, and directly proportional to the current through the coil. 
C)  inversely proportional to the number of turns in the coil, and inversely proportional to the current through the coil. 
D)  inversely proportional to the number of turns in the coil, and directly proportional to the current through the coil.

Exam 10: Magnetism and Electromagnetism

Faraday's law states that the:

The B-H curve plots:

Magnetomotive force in an electromagnet is increased by:

The force between carrying current parallel conductors:

What is the amount of flux in an 8-turn coil with 1.5 A of current if the reluctance is .04 x 106 At/Wb?

The Greek symbol is used to indicate the of a material in relation to flux lines.

The right hand rule is used for current-carrying conductors using electron flow.

Relative permeability of a magnetic material is a ratio of its:

What constitutes an electromagnet?

Reluctance varies:

The ease with which domains align and a magnetic field is established, in a given material, is called the material's:

The ability of a material to maintain a magnetized state without the presence of a magnetizing force is called:

An example of an electromagnetic device that also uses a permanent magnet is:

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

According to Faraday's law, if the rate of flux change quadruples, what happens to the induced voltage?

Calculate the induced voltage across a coil with 150 turns that is being cut by a magnetic field that is changing at a rate of 7 Wb/s.

There is 1.5 A of current through a coil consisting of 8 turns, what is the magnetomotive force mmF)?

A Tesla is equal to a meter per Weber.

Another name for a hysteresis loop is:

Magnetomotive force is:

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