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Physical Science 8 > Unit 5: Electricity > Flashcards

Unit 5: Electricity Flashcards

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1
Q

Static Electricity

A

When you rub shoes on carpet charge is transferred. Shoes are now charged. STATIC

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2
Q

How is the Law of Conservation in electricity?

A

The charges move. They are not created or destroyed.

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3
Q

What does the type of charge depend on?

A

Whether there are more protons (+) or electrons (-)

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4
Q

(++)
(–)
(+-)
(-+)

A

repel (like)
repel (like)
attract (opposites)
attract (opposites)

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5
Q

What does the force of the electricity depend on?

A

Distance. Closer = more force. Farther = weaker force
Ex. Electrostatic machine –> When bars are close together they discharge. When bars are far apart nothing happens (no shock)

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6
Q

What is lightning?

A

Collision of electrons with particles in the air. This creates light and heats the air up to 30,000C. The air expands and sound waves are created (thunder).

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7
Q

What device detects a charge on an object?

A

An electroscope

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8
Q

Lightning is the result of ________? Thunder is the result of _______?

A

Static electricity discharging

Heating the air molecules

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9
Q

What is the equation for ohm’s law? What do each of the variables stand for?

A 
V=IR
I=V/R
R=V/I
V: voltage (volts)
R: resistance (ohms)
I: current (amperes)
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10
Q

What are the devices used to prevent circuits from overheating?
Explain how they work.

A

Fuses: the wire melts opening the circuit
Breakers: metal bends and the current is switched off

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11
Q

When do the leaves of an electroscope separate?

A

When a charge is present the similar charge repels

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12
Q

What is the equation for electrical power? What do the variables stand for?

A

P=IV
P: Power (watts)
I: Current (amperes)
V: Voltage (volts)

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13
Q

What is the equation for electrical energy? What is the unit?

A

E=P(t)

kilowatt-hour

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14
Q

How does lightning occur to the ground?

A

Changes separate on the cloud. Induces ground to be opposite. Discharge is the bolt.

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15
Q

Why do we hear thunder?

A

Heating of the air to 30,000C causes the air to expand

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16
Q

Why does a spark reach the doorknob when you walk across the carpet?

A

When dry, static electricity builds up –> discharges –> metal conducts

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17
Q

Describe Atoms

A

Made up of protons and neutrons in the nucleus. Electrons on the outside. Protons are positive (+) and neutrons are neutral(0). Electrons are negative (-). Electrons can move. Atoms like to be neutral (same number of protons and neutrons).

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18
Q

How can you tell if Christmas lights are in a series or parallel circuit?

A

When you unscrew one bulb if all the lights go out it is in a series if only one bulb goes out it is parallel

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19
Q

Explain the electrostatic machine

A
  1. Turn the wheel
  2. Wheels spin in opposite directions
  3. As the metal brushes rub together the charges separate
  4. Static in the canisters
    Discharge
  5. Move the metal rods close together
    • –>
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20
Q

What’s the difference between static electricity and current?

A

Static: fraction of a second –> neutral
Current: flows due to voltage difference

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21
Q

Why are electrons the particles that move, not protons? Draw an atom to explain.

A

Protons: in nucleus
Electrons: cloud or shell outside
Loose-conduct

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22
Q

If more resistance, what happens to current? Explain?

A

Less current, more in the circuit, (people or bulbs)

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23
Q

What happens to the current if more voltage? How do you get more voltage?

A

More current, more batteries (power source), higher volts

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24
Q

Solve for OHMS law if I = 20 and R = 1.5

A 
OHMS law: V = IR, I = V/R, R = V/I
V = 20(1.5)
V = 30.0
I = 20 amperes
R = 1.5 ohms
V = 30.0 Volts
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25
Q

Electricity is __________ when electric ___________ accumulate on an object by gaining or losing __________ that move more easily in a(n) __________ than they do in a(n) _____________.

A 
Static
charges
electrons
conductor 
insulator
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26
Q

Electricity in the form of a ________ flows from object to object from _________ voltage to _______ voltage.

A

current
high
low

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27
Q

This voltage ___________ can be produced by a _______ or by a ___________ at a power plant.

A

difference
battery
generator

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28
Q

Electrical ___________ can be _________ with one _________ to flow through or they can be _________ with two or more ___________ for the electricity.

A 
circuits
series
loop
parallel
branches
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29
Q

In what type of circuit will the brightness of the bulbs be diminished as more bulbs are added?

A

A series circuit

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30
Q

In what type of circuit will both lights go out if one light is turned off?

A

A series circuit

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31
Q

What type of circuit is used to provide electricity to houses?

A

A parallel circuit

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32
Q

A negatively charged object has ___________ electrons than an object that is neutral.

A

more

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33
Q

Electrons flow from areas of _______ voltage to areas of _________ voltage

A

higher

lower

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34
Q

Voltage difference is measured in _________.

A

volts

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35
Q

Electrons passing through a lamp ______ some voltage as they light the lamp

A

lose

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36
Q

Voltage _______________ in all parts of a series circuit

A

is the same

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37
Q

The current in a circuit is measured in ______________

A

amperes

38
Q

Current is almost always the flow of ________

A

electrons

39
Q

When a dry cell is connected in a series, the flow of electrons moves from the __________ terminal to the _________ terminal

A

positive

negatice

40
Q

In a dry cell, the carbon rod releases electrons and becomes the ___________ terminal

A

positive

41
Q

The voltage difference between the two holes in a wall socket is ___________

A

120 volts

42
Q

A car battery is an example of a __________ cell

A

wet

43
Q

Resistance is measured in _____

A

ohms

44
Q

Copper has a __________ resistance to electron flow than tungsten

A

lower

45
Q

According to Ohm’s law, _______

A

I=V/R

46
Q

The symbol for ohm is _______

A

omega (upside down horseshoe)

47
Q

In the equation I=V/R, I is expressed in __________

A

amperes

48
Q

In the equation I=V/R, V is expressed in ________

A

volts

49
Q

THe _________ terminal of a dry cell identifies the location of the carbon rod

A

positive

50
Q

A wire with a resistance of 3 Ohms has a _________ resistance to electron flow than a wire with a resistance of 5 ohms

A

lesser

51
Q

If two copper wires are the same length, but different thicknesses, the _________ wire has greater resistance

A

thinner

52
Q

What are the two types of circuits?

A

Parallel

Series

53
Q

Definition of:
series circuit
parallel circuit

A

Series circuit: The current has only one loop to flow through.
parallel circuit: The current has more than one branch.

54
Q

Too many appliances in a circuit can cause a

A

fire

insulation to melt

55
Q

For protection, household circuits contain

A

fuses that melt a wire and open the circuit

circuit breakers the switch flips and the circuit is open

56
Q

Definition of electrical power

A

Rate at which electrical energy is converted to another form of energy

57
Q 
Unit of electrical power:
Name- 
Abbreviation- 
Term for 1,000 units-
Abbreviation for 1,000 units-
A

Watt
W
Kilowatt
KW

58
Q

Determining the electrical power of a circuit:
Expression-
Formula-

A

Power = current X voltage

P=IV

59
Q

A power rating lists the ___________ required to operate an appliance.

A

watts

60
Q

A closed path through which electrons can flow is _______

A

a circuit

61
Q

A fuse will melt if the _________ in a circuit becomes too high

A

current

62
Q

Current is almost always the flow of ________

A

electrons

63
Q

A current has two or more branches in a ___________

A

parallel circuit

64
Q

A car battery is an example of a ________

A

wet cell

65
Q

The tendency for a material to oppose the flow of electrons is called _________

A

resistance

66
Q

Current has only one loop to flow through in a ________

A

series circuit

67
Q

Current is measured in _________

A

amperes

68
Q

Electrical energy is equal to _________ X time

A

power

69
Q

Electrical power is equal to __________ X voltage difference

A

current

70
Q

Ohm’s law states that the current equals _______ divided by the resistance

A

voltage difference

71
Q

A dry cell is used in a flashlight to convert ________ to light

A

electrical energy

72
Q

Thin wires have a ___________ resistance to electron flow than thicker wire do

A

greater

73
Q

One thousand watts of power used in 60 minutes is _______

A

1 kilowatt-hour

74
Q

What are the 4 necessities for a circuit?

A
  1. Power Source (battery - pushes electrons)
  2. wires “conductor”
  3. device (like a light bulb)
  4. switch (on and off)
75
Q

Define insulator

A

Something that electricity does not move through easily

76
Q

Define conductor

A

Something that electricity does move through easily

77
Q

Define series

A

A circuit with only one path

78
Q

What are some insulators?

A

Clothes

Shoe laces

79
Q

What are some conductors?

A

Earring
Ring
Copper wire
lead on a pencil

80
Q

Define parallel

A

A circuit with two or more branches

81
Q

A measure of the amount of energy used to move 1 coulomb of electrons

A

voltage

82
Q

a complete path through which a current travels

A

electric circuit

83
Q

a measure of how difficult it is for an electric current to flow through a material

A

electric resistance

84
Q

The unit used to measure electric resistance is the

A

ohm

85
Q

Describe the relationship between electric resistance and the flow of electric current in materials

A

Good conductors have low resistance

86
Q

What type of copper wire has low resistance

A

short, thick wire

87
Q

If the current and resistance in a circuit are known, the voltage can be determined by

A

multiplying the current and resistance

88
Q

How to determine the amount of voltage each device is getting in a circuit

A

Divide the voltage by the number of devices

89
Q

The current flowing through an electric lantern is 0.25 A, and the resistance is 48 ohms. What is the voltage of the lantern battery

A

V=IR
V=0.25(28)
V= 12

12 Volts

90
Q

A small motor is labeled with a current rating of 3 A and a resistance of 40 ohms. What voltage does the motor run at?

A

V=IR
V=3(40)
V=120

120 Volts

91
Q

A DVD player that has a resistance of 40 ohms has a current of 0.1 A flowing through it. How many volts supply the DVD player?

A

V=IR
V=0.1(40)
V=4

4 Volts

92
Q

A neon sign that has a resistance of 50,000 ohms has a 0.06 A current passing through it. What is the voltage across the neon sign.

A

V=IR
V= 0.06(50,000)
V= 3,000

3,000 Volts

Physical Science 8 (1 decks)

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