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Question 1

What holds the electron in orbit around the nucleus?

Answer 1

A force of attraction

Question 2

Potential difference will exist between two points in the circuit that have a?

Answer 2

Difference in charge

Question 3

to produce a Voltage chemically, the two metals need to be made of?

Answer 3

Dissimilar metals

Question 4

Name 3 requirements needed to produce voltage by induction

Answer 4

1: Electrical conductor
2: Magnetic field
3: Relative movement

Question 5

What are the lines of force that pass through a space surrounding a magnet called?

Answer 5

lines of magnetic flux

Question 6

3 materials that mixed with steel, will produce stronger magnets

Answer 6

Aluminium,nickel, cobalt

Question 7

What is produced around a conductor when a current is passed through it?

Answer 7

lines of magnetic flux

Question 8

There are 3 requirements needed for magnetism to produce voltage by induction, they are?

Answer 8

Conductor
Magnetic field
Relative movement

Question 9

What direction does AC travel through a conductor?

Answer 9

both ways

Question 10

List 2 advantages of AC over DC

Answer 10

Wiring & equipment can be lighter.

Easier to transform

Question 11

The level to which the voltage or current rises to is called?

Answer 11

amplitude

Question 12

How are AC cycles per second expressed?

Answer 12

Hertz

Question 13

What are the values of the ships main electrical supplies?

Answer 13

450v 60hz 3 phase

Question 14

What is the frequency equation?

Answer 14

time(seconds)= 1/frequency

Question 15

List 4 advantages of an AC motor

Answer 15

less maintenance
more efficient
cheaper
more compact

Question 16

What is the main disadvantage of AC?

Answer 16

difficult to vary speed

Question 17

List the 2 main components of an AC motor

Answer 17

stator
rotor

Question 18

What causes movement in a 3 phase induction motor?

Answer 18

the rotating magnetic field produced by the stator

Question 19

What is the most common AC motor used in the navy?

Answer 19

squirrel cage

Question 20

List the components of a Squirrel cage

Answer 20

Non drive end bearing
Copper end ring
Copper bars
Drive end bearing

Question 21

How does the rotating magnetic field from the stator cause the rotor to rotate?

Answer 21

the rotating field induces a current

this current causes a magnetic field

the interaction between the two magnetic fields causes the rotor to ‘follow’ the rotating field

Question 22

What will happen if a running 3 phase AC motor were to lose 1 phase of input?

Answer 22

reduced speed
increased noise/ vibration
overheat

Question 23

What is Back EMF?

Answer 23

Movement of the conductor causes it to cut the magnetic field of the magnet meaning an EMF is induced into the conductor.

The induced EMF will be opposite in polarity to tue EMF applied to the conductor.

Question 24

What position must the carbon brushes be fixed and why?

Answer 24

The magnetic neutral axis (MNA)

to ensure no back EMF in the coil when the gap of the split ring passes the brush so there is no sparking.

Question 25

What are Inter-Poles and what do they do?

Answer 25

Poles similar to the main poles but smaller situated between the main poles and wound in series with the armature to offset varying current.

Question 26

What is the name given to materials in a solar panel?

Answer 26

semi conductor

Question 27

What’s the difference between Volts, Watts And Current?

Answer 27

Volts measure the electrical potential difference current is measure the flow of electrons watts measure the rate at which electrical energy is used volts x current

Question 28

What is Torque?

Answer 28

amount of turning moment exerted upon what is being turned

Question 29

What is an armature?

Answer 29

coils of wire which carries the alternating current

Question 30

What is magnetic flux?

Answer 30

lines of force around a magnet

Question 31

What is the Magnetic Neutral Axis (MNA)?

Answer 31

magnetic position centred in the magnetic feild between the opposite feild windings. can be charged by distortion.

Question 32

What is Field winding?

Answer 32

the insulated current-carrying coils on a field magnet that produce the magnetic field

Question 33

What is Lamination for?

Answer 33

improves efficiency

Question 34

Name the 3 classifications of DC motors.

Answer 34

series shunt compound

Question 35

What is a secondary cell?

Answer 35

can be re charged

Question 36

What is an electrolyte?

Answer 36

fluid carrying a electric charge

Question 37

What is the difference between magnetic flux and magnetic field?

Answer 37

magnetic flux is a measurement of magnetic field passing through

Question 38

What is an advantage of DC over AC?

Answer 38

more efficient

Question 39

Define power?

Answer 39

the rate of doing work

Question 40

The amount of torque produced by a motor depends on?

Answer 40

strength of magnetic field magnitude of armature current

Question 41

Electric power depends on?

Answer 41

voltage and current

Question 42

1 horsepower = ?

Answer 42

746 W

Question 43

Earth faults can be caused by?

Answer 43

low resistance between conductor and earth Dampness insulation becoming hard or brittle with age or heat accidental damage

Question 44

A transformer consists of 2 coils close together but insulated from one another. What are they called?

Answer 44

shell

Question 45

The 3 sets of windings of a 3-phase motor are usually connected in 2 which ways?

Answer 45

star or delta

Question 46

Describe the Compound wound motor.

Answer 46

combination of series and shunt motor series field winding’s connected in series with the amarture + shunt feild parallel. Good torque and regulated speed

Question 47

Name the 2 neutral axis associated with DC motors

Answer 47

Geometric + magnetic

Question 48

Why wont DC current work with transformers?

Answer 48

no change to the magnetic field