120102b Electricity

Question 1

This term describes a noisy, uncontrollable arc that flares from side to side.
a) arc voltage
b) arc blow
c) inductance
d) resistance

Answer 1

b) arc blow

Question 2

This term describes the influence exerted by a magnetic field on neighbouring bodies without physical contact.
a) voltage
b) amperage
c) frequency
d) inductance

Answer 2

d) inductance

Question 3

This is the fundamental unit of electricity that moves through a conductor when current is flowing.
a) resistors
b) electrons
c) conductors
d) rectifiers

Answer 3

b) electrons

Question 4

Which term describes the NEMA rating of a welding machine?
a) duty cycle
b) direct current
c) arc voltage
d) amperage

Answer 4

a) duty cycle

Question 5

Electrode positive means:
a) straight polarity
b) reverse polarity.
c) AC transformer.
d) alternating current.

Answer 5

b) reverse polarity.

Question 6

Electrons have a charge.
a) neutral
b) 12-volt
c) positive
d) negative

Answer 6

d) negative

Question 7

Which term measures the strength of a current of electricity?
a) amperage
b) voltage
c) electron
d) inductance

Answer 7

a) amperage

Question 8

What term describes a medium that provides an electrical path for current to flow
through?
a) cycle
b) circuit
c) conductor
d) core

Answer 8

c) conductor

Question 9

The electron flow theory states that electrons move from.
a) positive to negative
b) negative to positive

Answer 9

b) negative to positive

Question 10

This term describes a material that can stop current flow through itself.
a) inductor
b) inverter
c) conductor
d) insulator

Answer 10

d) insulator

Question 11

Which term describes the voltage output of the machine during welding?
a) arc rectification
b) arc blow
c) arc voltage
d) inductance

Answer 11

c) arc voltage

Question 12

When current flows through a coil wrapped around an iron core, what is created?
a) a magnetic field
b) reverse polarity
c) transformer rectifier
d) duty cycle

Answer 12

a) a magnetic field

Question 13

This device in a welding machine is designed to have a certain number of turns of wire.
a) circuit
b) core
c) coil
d) cycle

Answer 13

c) coil

Question 14

The main function of this device is to change AC to DC.
a) resistor
b) rectifier
c) relay
d) reactor

Answer 14

b) rectifier

Question 15

Electrode negative is:
a) straight polarity.
b) reverse polarity.
c) ac transformer.
d) alternating current.

Answer 15

a) straight polarity.

Question 16

This current flows in one direction only and has either a positive or negative value.
a) direct current
b) alternating current
c) open circuit voltage
d) arc voltage

Answer 16

a) direct current

Question 17

Which term describes a piece of equipment used to create electricity of sufficient volume for welding?
a) inductor
b) resistor
c) transformer
d) generator

Answer 17

d) generator

Question 18

Which is a graphical illustration that plots the relationship between voltage and amperage output of a welding power source?
a) open circuit voltage
b) volt-amp curve
c) electromotive force
d) duty cycle

Answer 18

b) volt-amp curve

Question 19

When no current is flowing in the circuit, but the machine is turned on, you can measure the:
a) open circuit voltage.
b) constant current.
c) alternating current.
d) volt-amp curve.

Answer 19

a) open circuit voltage.

Question 20

The speed at which AC changes direction is called the:
a) voltage.
b) amperage.
c) frequency.
d) resistance.

Answer 20

c) frequency.

Question 21

This term describes the property of an electrical conductor that opposes the flow of current.
a) resistance
b) inductance
c) voltage
d) amperage

Answer 21

a) resistance

Question 22

In welding, this term describes what is created when there is enough amperage and voltage to overcome the natural resistance to the flow of the electricity.
a) amp
b) volt
c) cycle
d) arc

Answer 22

d) arc

Question 23

List three (3) advantages of three-phase systems over single-phase systems.

Answer 23

a) constant power
b) smaller equipment
c) more efficient

Question 24

What phase of power supplies most industrial applications?
a) single-phase power
b) two-phase power
c) three-phase power
d) four-phase phase

Answer 24

c) three-phase power

Question 25

This welding machine transforms AC to DC. a) line transformer b) transformer rectifier c) DC generator d) AC transformer

Answer 25

b) transformer rectifier

Question 26

This term describes one complete revolution of the AC alternator. a) circuit b) core c) coil d) cycle

Answer 26

d) cycle

Question 27

What happens when mechanical energy is applied to a conductor and it moves across the magnetic lines of force in a magnetic field? a) Magnetism is generated. b) Electrical current is generated. c) Single-phase power is generated. d) Three-phase power is generated.

Answer 27

b) Electrical current is generated.

Question 28

These machines convert high voltage, low amperage to low voltage, high amperage by the use of a primary and a secondary coil. a) AC transformer b) AC generator c) DC generator d) AC alternator

Answer 28

a) AC transformer

Question 29

What does EMF stand for? a) electron movement force b) elementary motor force c) electromotive force d) electromotive factor

Answer 29

c) electromotive force

Question 30

Which term describes the typical sound of an AC transformer welding machine? a) turbine whine b) high-pitched scream c) buzz box d) whisper quiet

Answer 30

c) buzz box

Question 31

This type of welding machine is capable of changing DC to high frequency AC. a) AC generator b) DC rectifier c) DC generator d) inverter

Answer 31

d) inverter

Question 32

What is the function of the secondary winding on a transformer welder? a) to induce high frequency current b) to serve as a back-up in case the primary winding fails c) to step down the voltage d) to step down the amperage

Answer 32

c) to step down the voltage

Question 33

One advantage of an AC transformer welder is freedom from: a) undercut. b) arc blow. c) porosity. d) slag inclusions.

Answer 33

b) arc blow.

Question 34

What is the purpose of a sil icon-control led rectifier? a) to change AC to DC b) to change single-phase to three-phase c) to increase the welding speed on aluminum d) to change DC to AC

Answer 34

a) to change AC to DC

Question 35

What is one advantage of an AC-DC transformer-rectifier welding machine? a) Arc blow is not a problem. b) The purchase price is lower than for a transformer. c) You have a choice of polarity. d) It does not have to be kept clean and cool.

Answer 35

c) You have a choice of polarity.

Question 36

In Figure 33 the output voltage or current waveform to a load from a generator that uses slip rings is indicated by which diagram? a) A b) B c) C

Answer 36

a) A

Question 37

In Figure 33 the output voltage or current waveform to a load from a generator that uses a commutator is indicated by which diagram? a) A b) B c) C

Answer 37

c) C

Question 38

A DC motor generator produces what type of welding current? a) rectified b) AC c) DC d) high frequency

Answer 38

c) DC

Question 39

How can you change the polarity on an AC alternator welding machine? a) Switch the cables at the machine. b) Reverse the direction of the motor. c) Change the polarity taps on the reactor coils. d) An AC alternator has no fixed polarity.

Answer 39

d) An AC alternator has no fixed polarity.

Question 40

What is one advantage of an engine-driven generator welding machine? a) lower cost b) portability c) less noise d) less maintenance

Answer 40

b) portability

Question 41

What is one advantage of all transformer welding machines? a) The maintenance costs are lower b) There is no choice of polarity. c) They are not portable. d) The choice of electrode types is narrow.

Answer 41

a) The maintenance costs are lower

Question 42

These welding power sources immediately rectify the incoming AC to DC and then transistors create a higher frequency AC. The higher frequency AC is then rectified to extremely smooth DC. a) transformers b) generators c) buzz boxes d) inverters

Answer 42

d) inverters

Question 43

How did manufactures reduce the size and weight of transformers and generate significant energy savings over conventional power sources? a) rectifier technology b) generator technology c) inverter technology d) transformer technology

Answer 43

c) inverter technology

Question 44

What is an advantage of an inverter welding machine? a) small and lightweight b) generally cheaper to buy c) portability d) functions well in a dirty environment

Answer 44

a) small and lightweight

Question 45

What is a disadvantage of an inverter welding machine? a) poor arc starting characteristics b) higher input power requirements c) higher initial cost than transformers or rectifiers d) cannot be configured for automation

Answer 45

c) higher initial cost than transformers or rectifiers