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RADT 181 - Phys. 3 > Electromagnetism > Flashcards

Electromagnetism Flashcards

1
Q

A variable resistor to control current

A

Rheostat

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2
Q

The magnetic effect of electrocurrent was discovered by:

A

Oersted

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3
Q

Current is created by the flow of ____ from a negative terminal to a positive terminal

A

electrons

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4
Q

Current behaves as if ____ charges cause the flow

A

positive

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5
Q

The configuration of a coiled wire

A

solenoid

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6
Q

T/F: If you add an iron core to the solenoid, it will refine and organize the magnetic field even further.

A

True

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7
Q

Law of electromagnetism predicting how a magnetic field will interact with an electric circuit to produce an electromotive force

A

Faraday’s Law of Induction

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8
Q

Measures magnitude and direction of electric current

A

Galvanometer

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9
Q

An electric current is induced in a circuit if some part of that circuit is exposed to a changing magnetic field. The current this produces is:

A

Alternating current

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10
Q

Increasing the number of coils being affected by the magnetic field [increases/decreases] the voltage induced in the coils

A

Increases

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11
Q

If you double the number of coils being affected by the magnetic field, the voltage:

A

Doubles

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12
Q

Doubling the strength of the magnet will ____ the induced voltage

A

Double

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13
Q

Also, increasing the coil’s speed of motion through the field will [increase/decrease] the strength of the field

A

increase

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14
Q

If the motion of the wire is placed ____ to the magnetic field, the highest number of flux lines will interact with the wire causing the greatest current available.

A

Perpendicular

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15
Q

If the motion of the wire is at an ____ angle, then the current will be less as fewer lines of magnetic force will affect the wire over the same period of time

A

Oblique

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16
Q

The magnitude of the induced current depends upon:

A

1.The strength of the magnetic field
2. The velocity of the magnetic field as it moves past the conductor (wire)
3. The angle of the conductor to the magnetic field
4. The number of turns in the conductor (coils)

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17
Q

Happens when an uncharged metallic object experiences a shift in electrons when it is brought into the electric field of a charged object

A

Electric induction

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18
Q

The generation of an induced current that opposes any change in current existing in the circuit whether it an increase or decrease.

A

Self induction

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19
Q

The generation of an induced alternating current in a secondary coil by supplying an alternating current to a primary coil

A

Mutual induction

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20
Q

____ always opposes the changing current

A

Self induction

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21
Q

This process occurs when the alternating current within the induced circuit creates its own magnetic field that induces a second current to flow within the wire, but in the opposite direction

A

Self induction

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22
Q

Two types of electromagnetic induction:

A

Self induction, mutual induction

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23
Q

According to ____, an induced current flows in the opposite direction of the magnetic field change that produced it

A

Len’z law

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24
Q

T/F: It is not necessary to physically move a magnet near a coil to induce an electric current.

A

True

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25
Q

Can produce an electric current by rotating loops of wire in a fixed magnetic field

A

Magnetic generator

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26
Q

Coils of wire used in a magnetic generator in place of a single loop of wire

A

Armature

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27
Q

Solid round ring used to generate AC power

A

Slip ring

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28
Q

Rings with two open slits aligned at a plane 90 degrees perpendicular to the plane of the loop (changes AC to DC)

A

Commutator ring

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29
Q

Mechanism where an electric current is supplied to the loop instead of mechanical energy

A

Electric motors

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30
Q

Several fixed electromagnets arranged in pairs

A

Stator

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31
Q

located in the middle of the stator and composed of an iron core surrounded by coils

A

Rotor

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32
Q

Changes currents and electric potential into higher or lower intensities

A

Transformer

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33
Q

3 types of transformers:

A

Closed core, shell type, auto transformer

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34
Q

Transformer that increases voltage

A

Step up transformer

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35
Q

Study of stationary charges

A

Electrostatics

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36
Q

Electric fields radiate toward a ____ charge

A

Negative

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37
Q

The study of moving electric charges

A

Electrodynamics

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38
Q

A region around a charged particle within which it can exert a force or have a force exerted upon it by other charged particles

A

Electric fields

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39
Q

The force of attraction or repulsion of a magnetic material due to the arrangement of its atoms, particularly its electrons.

A

magnetism

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40
Q

Particles with opposite charged electric fields attract each other as positive charges will have electrical field lines going out of it, and negatively charged particles will have electrical field lines coming towards it. These are called:

A

Monopoles

41
Q

In magnetic materials, orbiting electron spin in one direction. Electrons spinning in one direction in this manner create tiny magnetic fields called ____ with a North Pole and a South Pole

A

Dipoles

42
Q

when a number of these dipoles (atomic magnets) align with each other, they create a grouping called a:

A

Magnetic domain

43
Q

Magnetic fields consist of lines of force in space called a:

A

Flux

44
Q

a measurement of the total magnetic field which passes through a given area. It’s created when magnetic dipoles orient in one direction to create a magnet

A

Magnetic flux

45
Q

Unit of measurement for magnetic field strength is the:

A

Tesla (T)

46
Q

T/F: Any charged particle in motion creates a magnetic field

A

True

47
Q

The magnetic field is ____ to the motion of the particle

A

perpendicular

48
Q

A magnetic field is a ____ loop moving with the charged particle

A

closed

49
Q

3 basic types of magnets:

A

natural magnets, artificial permanent magnets, electromagnets

50
Q

Natural magnets are also called:

A

Lodestones

51
Q

Manufactures magnets:

A

Artificial permanent magnets

52
Q

In its simplest form, it is an iron bar wrapped with a wire carrying an electric current

A

Electromagnets

53
Q

Weakly repelled by magnetic fields (water, mercury, gold, etc.)

A

Diamagnetic

54
Q

Not affected by magnetic fields (wood, glass, plastics, etc.)

A

nonmagnetic

55
Q

those weakly attracted to magnetic fields (plutonium, gadolinium, aluminum, etc.)

A

Paramagnetic

56
Q

materials that are strongly attracted to magnetic fields (iron, cobalt, nickel, etc.)

A

Ferromagnetic

57
Q

Two ways to induce a magnetic field:

A

Placing the material in a magnetic field; Rubbing the material against a permanent magnet

58
Q

The electric current through an X-ray tube is measured in:

A

milliamperes

59
Q

For an electric current to flow through a conductor, the electrons must be driven by:

A

A potential difference

60
Q

When a charged particle moves in a straight line, a magnetic field is created ____ to the particle motion

A

perpendicular

61
Q

The term electromagnetic induction refers to the production of:

A

An electric current

62
Q

The force between the poles of two bar magnets varies [x] with the distance between them

A

directly

63
Q

The fact that an electric current is induced if the conductor is in a changing magnetic field was discovered by:

A

Faraday

64
Q

The experimental link connecting electric and magnetic forces was first discovered by

A

Oersted

65
Q

When the right-hand rule is applied to a straight wire, the thumb indicates the direction of the:

A

Electric current

66
Q

T/F: Most magnets are still magnetic when broken.

A

True

67
Q

T/F: Most magnets are affected by another magnetic field.

A

True

68
Q

If two magnets are bought together, north-to-north poles will [a], whereas north- to-south poles will [b]

A

repel; attract

69
Q

Given a closed loop of wire with no electron flow, an electric current can be induced if:

A

A changing magnetic field is present

70
Q

To make an electromagnet stronger, a coil of wire is [x] an iron core.

A

wound around

71
Q

A difference between self-induction and mutual induction is that mutual induction requires [a] coils and self- induction requires only [b].

A

two; one

72
Q

The ability of an element in a circuit to reduce or imped the flow of electricity defines:

A

Resistance

73
Q

If a conductor is curved, the greatest amount of charge will be found:

A

at the area of the greatest curvature of the conductor

74
Q

Electrification by induction requires that the two objects:

A

are not at all in contact with each other

75
Q

Magnetic fields consist of lines of force known as ____

A

Flux lines

76
Q

An electric current produces a magnetic field that is __________ to the direction of the current

A

perpendicular

77
Q

T/F: Magnetic fields extend infinitely becoming weaker the further they travel away from their source

A

False

78
Q

Electric fields radiate out from a ____ charge

A

positive

79
Q

The study of moving electric charges typically focuses on the movement of:

A

Electrons

80
Q

Magnetism is the ability of certain materials to attract:

A

iron, cobalt, or nickel

81
Q

T/F: Magnetic flux travels from north to south inside a magnet.

A

False

82
Q

According to the laws of magnetism, how will the north pole of one magnet react to the south pole of another magnet if placed very close together?

A

They will attract

83
Q

Water is magnetically classified as which of the following?

A

Diamagnetic

84
Q

T/F: A stronger magnetic field will magnetize a ferromagnetic material more strongly.

A

True

85
Q

What is the right-hand rule used to determine?

A

Direction of magnetic flux

86
Q

The induction of a “back” current within the same coil is called:

A

Self-induction

87
Q

Transformer that decreases voltage

A

Step-down

88
Q

A type of transformer in which the coils are wound around a square or circular core to provide a continuous path for the magnetic field; it is insulated to help contain and direct the magnetic force lines.

A

Closed-core

89
Q

The most commonly used transformer; it “traps” the magnetic forces more efficiently in order to induce the strongest possible current in the secondary coil.

A

Shell transformer

90
Q

A device that raises or lowers voltage in the primary circuit, depending on the setting chosen on the machine’s control panel for the kilovolt peak voltage (kVp)

A

Autotransformer

91
Q

Moving a conductor by manual means within a magnetic field is the basic operation of a:

A

Generator

92
Q

T/F: The commutator ring in a generator design briefly breaks contact between the armature and circuit.

A

True

93
Q

What is the fundamental design difference between a generator and motor?

A

Electricity is applied to the armature of a motor.

94
Q

The external magnets of an induction motor are called:

A

Stators

95
Q

Basic transformer operation is based on what principle?

A

Mutual induction

96
Q

Which transformer design operates by self-induction?

A

Autotransformer

97
Q

In which device does a commutator ring serve to feed current through an armature the same direction each time?

A

Motor

98
Q

Converting mechanical energy to electrical energy is the purpose of which device?

A

Generator

99
Q

Transformers operate best with:

A

Direct current

RADT 181 - Phys. 3 (4 decks)

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