Week 2

Question 1

T or F: Inductance is the characteristic of an electrical conductor or circuit, which opposes a CHANGE in current flow.

Answer 1

True

Question 2

the unit of inductance is called the _______

Answer 2

henry

Question 3

T or F: The unit for measuring inductance (L) is the henry (h)

Answer 3

True

Question 4

Lenz’s Law

Answer 4

states that the induced emf in any circuit is always in a direction to oppose the effect that produced it.

Question 5

T or F: XL is the opposition to AC current due to the inductance in the circuit

Answer 5

True

Question 6

XL =

Answer 6

inductive reactance, measured inΩ

Question 7

f

Answer 7

frequency, measured in Hz

Question 8

L

Answer 8

inductance, measured in henrys

Question 9

counter-emf (Cemf) or back-emf

Answer 9

This induced voltage is in a direction so as to oppose the supply voltage

Question 10

T or F: the Cemf is acting like a resistance in reducing the current

Answer 10

T

Question 11

T or F: The inductive reactance of a coil is the number of ohms of resistance that the coil seems to offer as a result of a Cemf induced in it. Its symbol is XL to differentiate it from the DC resistance r.

Answer 11

True

Question 12

True or False: Terminal blocks shall be wired and mounted so the internal and external wiring does not cross over the terminals.

Answer 12

True

Question 13

True or False: One conductor only shall be terminated on the top of the terminal block for the conductors that are outside of the control panel.

Answer 13

True

Question 14

Alternating current (AC) control voltage shall be ______ volts or less, single phase.

Answer 14

120

Question 15

The color _____ with or without YELLOW stripes shall be used to identify the equipment _______ conductor where insulated or covered.

Answer 15

Green, grounding

Question 16

BLACK for Line and load circuits, AC or DC ____ volts and above.

Answer 16

150

Question 17

______ for ungrounded AC control conductors less than 150 volts

Answer 17

RED

Question 18

_____ for ungrounded DC control conductors

Answer 18

BLUE

Question 19

True or False: All pushbuttons shall be mounted above or to the left of their associated stop pushbuttons.

Answer 19

True

Question 20

What are the conductor sizes for:
1. Power circuits
2. Control circuits

Answer 20

1. # 14 AWG
2. # 16 AWG

Question 21

Start button operators shall be colored ______ and of the fully guarded type

Answer 21

BLACK

Question 22

Name the strength, or intensity, of a coil’s magnetic field depends on a number of factors:

Answer 22

1. The number of turns of the conductor
2. The amount of current flow through the coil
3. The ratio of the coil’s length to its width
4. The type of material in the core

Question 23

Solenoid action

Answer 23

converts electrical energy into mechanical work through electromagnetic forces

Question 24

Electromagnetic induction

Answer 24

It states that if a conductor cuts across lines of magnetic force, or if lines of force cut across a conductor, a voltage is induced across the ends of the conductor.

Question 25

True or False: The vertical axis shows the changes in magnitude by the variations of the voltage.

Answer 25

True

Question 26

What does the horizonal line on a graph showing a sine wave mean?

Answer 26

It shows time

Question 27

True or False: When a conductor cuts lines of force or lines of force cut a conductor, a voltage is induced across the conductor

Answer 27

True

Question 28

There must be ________ ________between the conductor and the lines of force in order to induce a voltage. (2 words)

Answer 28

relative motion

Question 29

The number of cycles in a given period of time, usually one second, is termed as the ___________.

Answer 29

frequency

Question 30

In the first half of rotation, this produces a _____ voltage and in the second half of rotation produces a _______ voltage

Answer 30

positive, negative

Question 31

The maximum number of flux lines is being cut at ___ degrees and this is the maximum value of voltage generated.

Answer 31

90