RT 205 Electromagnetic Flashcards Preview

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Flashcards in RT 205 Electromagnetic Deck (39):
1

Electrostatics

The branch of physics that deals with the force exerted by a static

2

Electric Field

An effect produced by an electric charge that exerts a force on charged objects in its vicinity

3

Fundamental Force

Material with the ability to attract iron

4

Orbital magnetic moment

Magnetic field perpendicular to the motion of a charged particle

5

Spin magnetic moment (Electron spin)

Magnetic effect established by electrons spinning on their axis

6

Magnetic Resonance Imaging

Disruption of the axial spinning and energy released as domains reorient themselves

7

Magnetic dipoles (aka Magnetic domains)

Groups of atoms with their net magnetic field moving in the same direction
(Theorized: about 10^15 atoms make up a dipole)

8

Magnetic Field (aka Lines of force (flux))

Force fields formed when magnetic dipoles orient to create a magnet

9

Lines of force always flow from ________ to _________ outside the magnet, and flow from ________ to _________ inside the magnet.

Flow from north to south outside the magnet
Flow from south to north within a magnet

10

SI unit: Lines of Force

Weber (Wb)

11

A magnet that is moved in space near a second magnet experiences a _____________.

Magnetic Field

12

The strength of the magnetic field is ________ when lines are closer, and ________ when they are farther apart.

Great when lines are closer, and weak when farther apart

13

Magnetic flux=

Field strength/area
Measure in Tesla (T) and Gauss (G)

14

1 Tesla= 10,000 G= 1 Wb/m^2

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15

The earth's magnetic field thought to originate with moving charges = ________T or _______G

= 0.0001 or 1 G

16

Classifications of Magnets
Iron oxide (magnetite) remains on earths magnetic fields

Natural

17

Classifications of Magnets
Manufactured from steel alloy
ex. Aluminum, nickel, cobalt

Artificial permanent

18

Classifications of Magnets
Temporary magnet produced by moving electric current (Electron current creates magnetic field)

Electromagnets

19

Laws of Magnetism
Repulsion- attraction

Like poles repel,Unlike poles attract
Like lines of force repel, Unlike lines of force attract

20

Laws of Magnetism
Inverse square law

Force between two magnetic fields directly proportional to product of their magnitudes and inversely proportional to square of distance between them.

21

Ease with which a material can be magnetized

Permeability

22

Ability of a material to stay magnetized

Retentivity

23

Ferromagnetic

Material with high magnetic permeability
Imposes little resistance to orientation in presence of a magnetic field
(Ex. Iron, Steel, Nickel)

24

Paramagnetic

Materials with a weak attraction to magnetic fields
-Low Permeability
(Ex. Platinum, Aluminum, MRI Contrast)

25

Diamagnetic

Weak form of magnetism exhibited only in presence of magnetic field
(Ex. Beryllium, bismuth, lead, water)

26

Nonmagnetic

Materials not affected by a magnetic field and cannot be magnetized
(Ex. Wood, Glass, Plastic)

27

A device that stores energy and makes it available in an electrical form

Battery

28

A device for creating or storing electrical energy composed of several similar (usually identical) cells that are connected together

Electrical battery

29

Electrical cell

A single such unit, possibly one cell in a battery of multiple cells or possibly the entire device

30

1V=__ Joule/Coulomb

1 V= 1 Joule/Coulomb

31

A coil consisting of a series of loops, and serves to increase the flux density

Solenoid coil

32

Electromagnetic relay

Similar to circuit breakers
- Protect Technologists from high voltage when flowing

33

Three ways to create motion between lines of force and a conductor

1. Magnetic field
2. Conductor
3. Relative motion

34

Methods to Induce a Current
1. Move conductor through stationary unchanging strength magnetic field
2. Move magnetic lines of force across conductor with unchanging strength magnetic field
3. Vary strength of stationary magnetic field through conductor

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35

Four Factors of Faraday's Law

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

36

Lenz's Law

An induced emf generates a current that induces a counter magnetic field that opposes the magnetic field generating the current

37

Mutual Induction

The production of an electromotive force (emf) or voltage in an electric circuit caused by a changing magnetic flux in a neighboring circuit.

38

Self-Induction

Property whereby an electromotive force is induced in a circuit by a variation of current in the circuit itself.

39

Opposition to the flow of AC current produced by an inductor. (Measured in Ohms and varies in direct proportion to frequency)

Inductive Reactance