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Flashcards in Ch 1 Deck (114)
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1

The Law of Attraction and Repulsion of magnets states:

Like poles repel each other and unlike poles attract each other

2

This is the result of the atomic bonding of two or more atoms

Compounds

3

What would you use to protect the electrical equipment in a building?

Surge protectors

4

What will a magnet align itself with if it is hung freely from a piece of string?

Earth's magnetic field

5

What keeps electrons from breaking out of their orbit around the nucleus?

Law of electrical charges

6

When a magnet is hung freely, what do you call the end that is pointing north?

north-seeking pole

7

What do you call a switch that uses an electromagnetic field to open or close a set of contacts?

Electromagnetic Relay

8

When atoms of elements combine they produce _____

Compounds

9

Some crystalline materials produce a small electrical voltage when bending or twisting pressure is applied to them, what is the effect?

Pressure (Piezoelectricity)

10

Illumination is produced when a source of energy strikes phosphorus materials

Phosphorescent illumination

11

The conductor that rotates between the stationary magnetic field poles of the stator is called what?

Rotor or armature

12

What is the maximum let-go threshold for women and men?

10mA and 16 mA

13

What is the only naturally occurring magnet?

Lodestone

14

When energy is applied to valence electrons, it is divided evenly among them, how does that affect them?

Fewer valence electrons for a given amount of energy means each valence electron receives more available energy.

15

What causes the armature of a dc motor to rotate?

The repelling forces of similar magnetic polarities and the attracting force of opposing polarities.

16

How many shells are around the nucleus of an atom where electrons orbit?

7

17

This is the process where heat is applied to dissimilar metals that are joined together to produce about 5 to 30 thousandths of a volt.

Thermoelectric effect

18

(T/F) A magnet will affect a compass?

True

19

What forces the rotor to rotate in a generator?

Prime Mover

20

What materials make up permanent and temporary magnets?

Hard Steel & Soft Iron

21

What do you call the stationary magnetic field around a dc motor?

Stator

22

Compounds can change the _____ _______ of the individual atoms

electrical characteristics

23

What does a clamp-on AC ammeter detect?

The rising and falling and falling of the magnetic field around the conductor.

24

What dictates the distance an arc can jump?

Voltage & Dielectric

25

(T/F) Lightning strikes both metallic and nonmetallic objects with the same frequency?

True

26

(T/F) Both AC and DC electromagnetic fields are used to operate motors and relays

True

27

(T/F) Ions can be positively or negatively charged?

True

28

The smallest particle of a compound is called what?

Molecule

29

(T/F) You cannot have normally open and normally closed contacts in a single relay?

False

30

What is lightening protection intended to protect?

The building itself, not the electrical equipment.