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Rad100 > Chpt 5 Part 4 > Flashcards

Chpt 5 Part 4 Flashcards

1
Q

Works by moving a magnet near a coil of wire and electricity is induced in the coil of wire

A

Generators

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2
Q

Converts mechanical energy into electric energy

A

Generators

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3
Q

Examples of mechanical energy

A

Steam, water, nuclear energy, gas/coal/oil, wind, solar

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4
Q

What are the two components of a generator?

A

Field magnet
Armature (conductor)

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5
Q

What moves (mechanical energy) through the magnetic field that induces current in the armature

A

Armature (conductor)??

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6
Q

For a simple generator:
What provides the magnetic field

A

Field magnet

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7
Q

For a simple generator:
What moves through the magnetic field

A

Armature

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8
Q

For a simple generator:
The armature is attached to what

A

Slip rings

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9
Q

For a simple generator:
What allows the slip rings to stay in contact with the wire to the load

A

Carbon brushes

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10
Q

Generators produce what type of current?

A

AC

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11
Q

(T/F) one cycle is one full rotation of the armature

A

True

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12
Q

Resistance in AC (3)

A

Inherent
Inductive
Capacitive

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13
Q

Inductive resistance caused by the magnetic field does what

A

expands and contracts over its own conductor

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14
Q

Capacitive resistance is caused by the change in what

A

change in polarity of a capacitor in the circuit

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15
Q

Does DC or AC use commutator rings instead of slip rings

A

DC

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16
Q

Rings act like a ____, changing the _____ of the contact on the loop in the wire. Produces a pulsating __________

A

Switch
Polarity
Direct current

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17
Q

Which type of current (DC/AC) uses multiple coils and why

A

DC
it pulses so you need multiple to keep the current / voltage up

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18
Q

A motor that converts electrical energy to mechanical energy

A

Electric motor

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19
Q

How does an electric motor work?
Current is passed through a ____ and produces a _______ creating motion in the ______

A

Wire
magnetic field
Conductor

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20
Q

Flemings left hand generator rule is used to determine what?

A

Direction of motion in a conductor

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21
Q

Two types of electric motors

A

DC motors
AC motors (synchronous and induction)

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22
Q

Motor turns at the same speed as the incoming current (60 hz)
Used in clocks and in some X-ray exposure timers

A

Synchronized AC Motors

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23
Q

Has two parts (stator and rotor)
As the current creates a changing magnetic field, the rotor is rotated

A

Induction AC motor

24
Q

What has the pair of electromagnets arranged around the rotor and what has the bars of copper around an iron core

A

Stator
Rotor

25
Q

An electromagnetic device that changes the voltage and current in a circuit through the process of mutual induction. And it only works with what?

A

Transformers
AC

26
Q

The primary side of the transformer is the side in which the _______ is flowing. The secondary side is where the _____ is ______

A

Original emf
EMF is induced

27
Q

Amount of induced emf (voltage) is determined by what

A

The number of turns or coils in the wire

28
Q

Transformers law formula

A

Vs/Vp = Ns/Np

29
Q

If the number of turns on the primary side is less than the number of turns on the secondary side what happens to the voltage?

A

Goes up
Step up transformer

30
Q

Transformers are used to change the voltage but because if Ohms law they also change what

A

Current

31
Q

Transformers law but for current

A

Is/Ip = Np/Ns OR Is/Ip = Vp/Vs

32
Q

How efficient are transformers

A

95%
5% to power loss

33
Q

5 types of transformers

A

Air core, open core, closed core, shell type, auto transformer

34
Q

Simplest type of transformer
- 2 sets of coils side by side

A

Air core

35
Q

Iron bars are placed within the coils, increased magnetic field, more efficient than air core, some magnetic field loss at the ends

A

Open core

36
Q

Minimizes the loss of the magnetic field at the ends, more efficient and expensive than open core, used most often in X-ray equipment (step up and down)

A

Closed core

37
Q

Most expensive. Most advanced and efficient, used by industry or electric companies, most commonly used transformer

A

Shell type

38
Q

Variable transformer, may act as a step up or down by varying the number of turns that are tapped, always placed btn AC source and the primary side of the high voltage transformer, single coil with coil wrapped around

A

Auto transformer

39
Q

3 main causes of transformer loss

A

Resistance : heat
Hysteresis : alternating mag fields cause current to alt causing resistance
Eddy current : current opposing the mag field that induced them

40
Q

3 devices controlling current

A

Choke coil
Rheostat / potentiometer
Saturable reactor

41
Q

(T/F) a rheostat is a variable resistor

A

True

42
Q

(T/F) by changing the resistance in the circuit and keeping the voltage constant the current changes

A

True
Ohms law

43
Q

Reverse bias is when what happens in the X-ray tube

A

When electrons try to go from anode to cathode
Causes damage

44
Q

Process of converting AC to DC

A

Rectification

45
Q

What allows electrons and current to flow in one direction
- The two types

A

Rectification
Vacuum tube, solid state diode (most common)

46
Q

Two types of semiconductors

A

P type : positively charge. holes that attract and hold electron
N type : negatively charged. Looser bound electron that moves freely

47
Q

(T/F) electron will flow from n to p but not p to n

A

True
Current will only flow in one direction

48
Q

A series of p-n junctions, a rectifying semiconductor

A

Diode

49
Q

For a diode electrons will move from ______ as current moves

A

Side to side

50
Q

More complex semiconductor, used for high speed switching if primary high voltage X-ray circuit

A

SCR
silicon controlled rectifier
AKA thyristor

51
Q

Two types of rectification

A

Half and full wave

52
Q

Only one rectifier needed, may use two, uses half the AC and changes it to pulsating current
(Rectification type)

A

Half wave

53
Q

Minimum 4 rectifiers needed, form rectification bridge, used in modern X-ray
(Rectification type)

A

Full wave

54
Q

Converts the opposing half of the incoming electron flow so that electrons are always moving in the same direction

A

Full wave rectification

55
Q

Which rectifier allows the ability to use higher mA and kVp settings

A

Full wave

Rad100 (10 decks)

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