Test 1 Magnetism, Motors, Generators

Question 1

How do you de-magnetize magnetic material

Answer 1

Hitting it with a hammer, and/or heat

Question 2

Magnetic inductors oppose a change in?

Answer 2

Current

Question 3

1 Horsepower (HP) is equal to how many Watts?

Answer 3

746W

Question 4

What DC motor has the best Torque Characteristics

Answer 4

Series motor

Question 5

What is the name of a natural Magnet

Answer 5

Magnetite/lodestone

Question 6

What type of voltage is in a rotating generator

Answer 6

AC voltage

Question 7

Other DC motor types?

Answer 7

Permanent Magnet
DC servo
Brushless

Question 8

What is the opposing force in a motor?

Answer 8

CEMF (counter electromotive force)

Question 9

What shape are field windings?

Answer 9

Square

Question 10

Unlike poles do what?

Answer 10

Attract

Question 11

Like poles do what?

Answer 11

Repel

Question 12

Electromagnetism occurs when current passes through?

Answer 12

The Conductor

Question 13

What does the Commutator do?

Answer 13

Changes AC to DC
And
Maintains the proper polarity of the dc voltage

Question 14

Brushes ride against what component?

Answer 14

The Commutator

Question 15

How can you compensate for armature reaction

Answer 15

• Compensating Windings
• Adjust brushes to compensate for new point of neutral plane
• Interpoles

Question 16

Another term for armature?

Answer 16

Rotor

Question 17

The amount of voltage induced in in a conductor is affected by

Answer 17

• Turns of wire
• Strength of magnetic field
• Speed of cutting action

Question 18

The time constant for voltage to be fully induced?

Answer 18

5 times

Question 19

How to change the direction of the armature

Answer 19

Reverse the connections (change the Armature leads)

Question 20

In the right hand rule, what does the middle finger indicate?

Answer 20

Direction of Current

Question 21

What current causes excessive heat in the metals core material

Answer 21

Eddy current

Question 22

Lenz’s law states what?

Answer 22

The direction ofInduced current will oppose the motion that caused it

Question 23

Interpoles can be found in between?

Answer 23

Between the main poles

Question 24

How is the shunt field connected to the armature

Answer 24

In parallel

Question 25

2 methods to prevent voltage spikes

Answer 25

Diodes and Resistors

Question 26

What is permeability?

Answer 26

The ability to conduct magnetism

Question 27

Large spikes of voltage can be used for what?

Answer 27

Cow Fences

Question 28

Induction occurs when what passes through the magnetic field?

Answer 28

Conductor

Question 29

Separately excited shunt field is a shunt field that has

Answer 29

A different power supply

Question 30

Motors use what to rotate the armature?

Answer 30

Attraction and repulsion

Question 31

How do you control field excitation in a series shunt field motor?

Answer 31

Rheostat (variable resistor)

Question 32

Losses in a motor are?

Answer 32

• Windage Losses • I^2 R • Bearing Friction

Question 33

3 factors that affect output voltage of a DC generator

Answer 33

Conductor loops in the armature Armature speed Magnetic field strength

Question 34

Easily magnetized materials are known as?

Answer 34

Ferromagnetic

Question 35

What is it called when magnetism is still left in a motor that has been shut off?

Answer 35

Residual magnetism

Question 36

Difference between generator and motor?

Answer 36

Generator: Converts mechanical energy into electrical Motor: Converts electrical energy into mechanical

Question 37

What is coercive force?

Answer 37

A materials ability to stay magnetized after the magnetic force is removed

Question 38

What is flux density?

Answer 38

The magnetic field strength of the lines of force

Question 39

What is the north poles true polarity?

Answer 39

South polarity

Question 40

How can you produce AC voltage?

Answer 40

Slip rings

Question 41

Unit of measurement for an inductor?

Answer 41

Henry

Question 42

Compound Generator is made up of _______ Shunt and ______ Shunt.

Answer 42

Long and Short

Question 43

Left hand rule, what does the middle finger signify

Answer 43

Current

Question 44

What is it called when there is 0 Volts in the commutator?

Answer 44

Neutral Plane

Question 45

When the North Pole and South Pole don’t line up with the true magnetic poles

Answer 45

Declination

Question 46

How is a series motor connected?

Answer 46

In Series