Motors

Question 1

? is used to convert electrical energy to a rotating mechanical force on a motor’s shaft.

Answer 1

Electromagnetism

Question 2

? magnets are used more often than electromagnets in motors, transformers, and solenoids.

Answer 2

Temporary

Question 3

Magnetic flux is densest and magnetic force is strongest at the ? of a magnet.

Answer 3

Poles

Question 4

A ? is surrounded by a magnetic field that enters the south and exits the north pole.

Answer 4

Bar magnet

Question 5

The molecular theory of magnetism states that ? materials are made up of a very large number of molecular domains that can be arranged in either a disorganized or organized manner.

Answer 5

ferromagnetic

Question 6

The relative permeability of air is ?

Answer 6

1.0000004

Question 7

A(n) ? material is a material that can be very weakly magnetized in the opposite direction when a magnetic field is applied.

Answer 7

paramagnetic

Question 8

Electromagnetism is a ? magnetic force.

Answer 8

Temporary

Question 9

? magnets may be demagnetized by high temperatures.

Answer 9

Permanent

Question 10

For an electromagnet, a more permeable core strengthens the ? .

Answer 10

concentration of magnetic flux

Question 11

? is the condition where substantially all the magnetic domains in a magnetic core are aligned with the field and any increases in current no longer result in a stronger electromagnet.

Answer 11

Saturation

Question 12

With DC, both the current and magnetic field applied to a conductor start at ? and increase almost instantly to maximum value when a switch is closed; both drop to ? when the switch is opened.

Answer 12

• zero
  -zero

Question 13

Every time the current passes the ? point of the AC sine wave, the direction of current flow and polarity of the magnetic field change.

Answer 13

Zero

Question 14

The theory that current flows from the negative terminal to the positive terminal is called ? current flow.

Answer 14

Electron

Question 15

The requirements for induction are: ? , a magnetic field, and relative motion between the conductor and the magnetic field.

Answer 15

A conductor

Question 16

The ? rule is an explanation of the direction of a magnetic field around a coil relative to the direction of the current in the coil, where a left hand is used to illustrate the relationship.

Answer 16

left-hand coil

Question 17

The left-hand ? rule describes the direction of a magnetic field around a conductor relative to the direction of the current in the conductor.

Answer 17

Conductor

Question 18

? is the ability of an inductor (coil) in one circuit to induce a voltage in another circuit or conductor.

Answer 18

Mutual induction

Question 19

With a DC motor, a ? is used to reverse the current direction, which keeps the current flowing in one direction (DC) through the windings to keep the polarity correct in order to interact with the main fields.

Answer 19

commutator

Question 20

? law states that the polarity of induced voltage is such that it produces a current whose magnetic field opposes the change that produced it.

Answer 20

Lenz’s

Question 21

The ability of a material to conduct magnetic flux is its ? .

Answer 21

permeability

Question 22

Mutual induction is the ability of an inductor (coil) in one circuit to ? a voltage in another circuit or conductor.

Answer 22

Induce

Question 23

The ability of a material to retain residual magnetism is called ? .

Answer 23

permanence

Question 24

? Is a force by which materials exert an attraction or repulsion on other materials.

Answer 24

Magnetism

Question 25

? A substance that produces a magnetic field.

Answer 25

Magnet

Question 26

? A force produced by a magnet that exerts a force on moving electric changes or no other magnets.

Answer 26

Magnetic field

Question 27

? A magnet that can hold its magnetism for a long period.

Answer 27

Permanent magnet

Question 28

? A magnet that retains only trace amounts of magnesium after a magnetizing force has been removed.

Answer 28

Temporary magnetic

Question 29

? Is a measure of the ability of a magnetism after the magnetizing force has been removed.

Answer 29

Retentivity

Question 30

? The invisible lines of force that make up the total quantity of a magnetic field.

Answer 30

Magnetic flux or field flux

Question 31

? The amount of concentration of magnetic flux through a specific area.

Answer 31

Flux density

Question 32

? A ferromagnetic nonconducting ceramic alloy with high permeability.

Answer 32

Ferrite

Question 33

? Can be energized or de-energized by applying or removing an electric current.

Answer 33

Electromagnet

Question 34

? Are used in many electrical devices.

Answer 34

Electromagnets

Question 35

? The total amount of a magnetic field.

Answer 35

Magnetic flux

Question 36

? Description of current flow as the flow of electrons from the negative terminal to the positive terminal of a power source.

Answer 36

Electron current flow

Question 37

When a AC source voltage ? And the magnetic flux ? Around an inductor, an opposing voltage, or counter-electromotive force (CEMF), is induced in the circuit.

Answer 37

-rises
-expands

Question 38

? States the polarity of the induced voltage is such that it produces a current whose magnetic field opposes the change that produces it.

Answer 38

Lenz’s law

Question 39

The interaction between a ? Around one coil and a second coil induces a current in the second coil.

Answer 39

Magnetic field

Question 40

? In the second coil creates its own magnetic field that opposes the initial magnetic field.

Answer 40

Induced current

Question 41

? In a conductor creates a magnetic field around the conductor. When the conductor is placed within a ? Between poles, the two interact. On one side of the conductor, the fields combine and become concentrated, creating a strong magnetic field. On the other side of the conductor, the field oppose and cancel, creating a weak magnetic field. The distortion creates a thrust that pushes the conductor out of the magnetic field.

Answer 41

-current
-magnetic field