Chpt 5 Part 4

Question 1

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

Answer 1

Generators

Question 2

Converts mechanical energy into electric energy

Answer 2

Generators

Question 3

Examples of mechanical energy

Answer 3

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

Question 4

What are the two components of a generator?

Answer 4

Field magnet
Armature (conductor)

Question 5

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

Answer 5

Armature (conductor)??

Question 6

For a simple generator:
What provides the magnetic field

Answer 6

Field magnet

Question 7

For a simple generator:
What moves through the magnetic field

Answer 7

Armature

Question 8

For a simple generator:
The armature is attached to what

Answer 8

Slip rings

Question 9

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

Answer 9

Carbon brushes

Question 10

Generators produce what type of current?

Answer 10

AC

Question 11

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

Answer 11

True

Question 12

Resistance in AC (3)

Answer 12

Inherent
Inductive
Capacitive

Question 13

Inductive resistance caused by the magnetic field does what

Answer 13

expands and contracts over its own conductor

Question 14

Capacitive resistance is caused by the change in what

Answer 14

change in polarity of a capacitor in the circuit

Question 15

Does DC or AC use commutator rings instead of slip rings

Answer 15

DC

Question 16

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

Answer 16

Switch
Polarity
Direct current

Question 17

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

Answer 17

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

Question 18

A motor that converts electrical energy to mechanical energy

Answer 18

Electric motor

Question 19

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

Answer 19

Wire
magnetic field
Conductor

Question 20

Flemings left hand generator rule is used to determine what?

Answer 20

Direction of motion in a conductor

Question 21

Two types of electric motors

Answer 21

DC motors
AC motors (synchronous and induction)

Question 22

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

Answer 22

Synchronized AC Motors

Question 23

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

Answer 23

Induction AC motor

Question 24

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

Answer 24

Stator
Rotor

Question 25

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

Answer 25

Transformers AC

Question 26

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

Answer 26

Original emf EMF is induced

Question 27

Amount of induced emf (voltage) is determined by what

Answer 27

The number of turns or coils in the wire

Question 28

Transformers law formula

Answer 28

Vs/Vp = Ns/Np

Question 29

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?

Answer 29

Goes up Step up transformer

Question 30

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

Answer 30

Current

Question 31

Transformers law but for current

Answer 31

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

Question 32

How efficient are transformers

Answer 32

95% 5% to power loss

Question 33

5 types of transformers

Answer 33

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

Question 34

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

Answer 34

Air core

Question 35

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

Answer 35

Open core

Question 36

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)

Answer 36

Closed core

Question 37

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

Answer 37

Shell type

Question 38

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

Answer 38

Auto transformer

Question 39

3 main causes of transformer loss

Answer 39

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

Question 40

3 devices controlling current

Answer 40

Choke coil Rheostat / potentiometer Saturable reactor

Question 41

(T/F) a rheostat is a variable resistor

Answer 41

True

Question 42

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

Answer 42

True Ohms law

Question 43

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

Answer 43

When electrons try to go from anode to cathode Causes damage

Question 44

Process of converting AC to DC

Answer 44

Rectification

Question 45

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

Answer 45

Rectification Vacuum tube, solid state diode (most common)

Question 46

Two types of semiconductors

Answer 46

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

Question 47

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

Answer 47

True Current will only flow in one direction

Question 48

A series of p-n junctions, a rectifying semiconductor

Answer 48

Diode

Question 49

For a diode electrons will move from ______ as current moves

Answer 49

Side to side

Question 50

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

Answer 50

SCR silicon controlled rectifier AKA thyristor

Question 51

Two types of rectification

Answer 51

Half and full wave

Question 52

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

Answer 52

Half wave

Question 53

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

Answer 53

Full wave

Question 54

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

Answer 54

Full wave rectification

Question 55

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

Answer 55

Full wave