Test 3- Electrodynamics Second Powerpoint

Question 1

Define Electricity:

Answer 1

The continuous flow of electrons along the surface of a conductor

Question 2

Define Electrodynamic:

Answer 2

The study of flowing electrical current

Question 3

Define Current:

Answer 3

The flow of loosely-bound, outer shell electrons when a potential difference (voltage) is applied

Question 4

Define Conductivity:

Answer 4

A materials ability to transmit electrical current

A conductor is, any material through which energy flows easily

Question 5

Conductors allow electricity to pass through easily

Give some examples

Answer 5

Copper
Sliver
Aluminum
Brass
Water

Question 6

Insulators (dielectrics): Resist the flow of electricity

Give some examples

Answer 6

Rubber
Glass
Plastic
Dry wood

Question 7

Symbols and Functions of electric circuit
elements

Slide 9

(Make Quizlet)

Question 8

Although we usually think of electrical current as a steady flow of electrons, at the atomic level…. What we we think of it as?

Answer 8

Loosely bound electrons in the outermost shells actually “Leap Frog” from one atom to the next in sequence

Question 9

Current is:

Answer 9

Mathematically, the rate of flow of electrons

Electrons per second
Coulombs per hour

Question 10

Circuit=

Answer 10

Circle!
To have a circuit, conductors must pass from the voltage source (battery) through all devices and back to the source.
If the circuit is broken at any point, electricity stops flowing throughout the circuit

Question 12

Does a battery create electrons?

Answer 12

No!
It only pumps them out one end and pulls them in from the other end.
This pumping movement fails if the circuit is not complete

Question 13

To have a circuit, at least 3 components are required:

Answer 13

1) A Conductor
2) A source of EMF (electromotive force)
3) A device to be operated that acts as an electrical resistor in the circuit

Question 14

An electrical switch is just a method of ___

Answer 14

Breaking the circuit

Question 15

What are the two general types of circuit layouts?
Example them

Answer 15

1) Series- All decided are connect in a row, one after another along the same wire
- If one device burns out, the entire circuit is broken and current stops

2) Parallel- Devices are connected each in a separate brand of the wire, which splits off from the original conductor
- Other branches of the circle are unaffected if one device burns out
* Christmas lights are a good example

Question 16

The relationship between electrical resistance, pressure and flow are described by the formula:

Answer 16

V= IR

V= Voltage
I= Amperage (current)
R= Resistance in a particular circuit

Question 17

OHM’S LAW FORMULA

Voltage and current are ____ to each other

Answer 17

Directly Proportional

• if pressure doubles, the amount of current flowing doubles

Question 18

Voltage and resistance are ____ to each other

Answer 18

Directly Proportional
- To maintain the flow, If resistance is doubled, pressure must also be doubled

Question 19

Amperage and resistance are___ to each other

Answer 19

Inversely Proportional

If resistance doubles, the amount of current flowing is cut in half

Question 20

Power, in general is defined as the rate at which:

Answer 20

Work is done

Question 21

Direct Current:

Answer 21

Electrons always flow in the same direction in a steady stream

Question 22

Alternating Current (AC):

Answer 22

Electrons oscillate back and forth

Question 23

Electric Generators:

Answer 23

Convert mechanical energy into electric charge

Question 24

A current is inducted in a conductor that is moved through a magnetic field ___ or ___ to the magnetic field lines

Answer 24

Across or Perpendicular

Question 25

If the conductor moves ___ to the magnetic field, there is no current induced in the conductor.

Answer 25

Parallel

Question 26

AC Generator kVp=

Answer 26

peak voltage

Question 27

A motor converts ____ into ___

Answer 27

electric charge into mechanical energy

Question 28

Generators convert ___ into ____

Answer 28

Mechanical energy into electrical energy

Question 29

What are the two part to every motor?

Answer 29

The Rotor: Spins The Stator: Stationary coils of wire surrounding the rotor

Question 30

What is an induction motor?

Question 31

What do transformers do?

Answer 31

Alter the voltage or the amperage of electrical current

Question 32

Mutual induction occurs when:

Answer 32

Two coils are placed in proximity and varying current supplied to the first coil (primary) induces a similar flow in the second coil (secondary)

Question 33

The unit of mutual inductance is the:

Answer 33

Henry

Question 34

Mutual Induction Flow occurs in secondary coil because the ___ current alternates.

Answer 34

Primary

Question 35

What is the phenomenon in which a change in electric current in a coil produced an induced emf in the coil itself?

Answer 35

Self Induction

Question 36

Self inducted emf in a foul is ____ to the rate of change of electric current in the coil.

Answer 36

Directly Proportional

Question 37

Transformers consists of:

Answer 37

a pair of wire coils joined together around an iron core

Question 38

Transformers Transform ____ and current into higher and lower intensities.

Answer 38

Electric Potential

Question 39

What is used to change low voltage into higher voltages or vice versa in an AC circuit?

Answer 39

A transformer

Question 40

___ transformers have a turns ratio greater than 1

Answer 40

Step Up Transformers

Question 41

___ have turns ratio less than 1

Answer 41

step down transformers

Question 42

What are the three types of transformers?

Answer 42

Closed-core transformer Auto transformer Shell type transformer

Question 43

Review Summary Slides at the end of