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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
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) _____________.
``` Static charges electrons conductor insulator ```
26
Electricity in the form of a ________ flows from object to object from _________ voltage to _______ voltage.
current high low
27
This voltage ___________ can be produced by a _______ or by a ___________ at a power plant.
difference battery generator
28
Electrical ___________ can be _________ with one _________ to flow through or they can be _________ with two or more ___________ for the electricity.
``` circuits series loop parallel branches ```
29
In what type of circuit will the brightness of the bulbs be diminished as more bulbs are added?
A series circuit
30
In what type of circuit will both lights go out if one light is turned off?
A series circuit
31
What type of circuit is used to provide electricity to houses?
A parallel circuit
32
A negatively charged object has ___________ electrons than an object that is neutral.
more
33
Electrons flow from areas of _______ voltage to areas of _________ voltage
higher | lower
34
Voltage difference is measured in _________.
volts
35
Electrons passing through a lamp ______ some voltage as they light the lamp
lose
36
Voltage _______________ in all parts of a series circuit
is the same
37
The current in a circuit is measured in ______________
amperes
38
Current is almost always the flow of ________
electrons
39
When a dry cell is connected in a series, the flow of electrons moves from the __________ terminal to the _________ terminal
positive | negatice
40
In a dry cell, the carbon rod releases electrons and becomes the ___________ terminal
positive
41
The voltage difference between the two holes in a wall socket is ___________
120 volts
42
A car battery is an example of a __________ cell
wet
43
Resistance is measured in _____
ohms
44
Copper has a __________ resistance to electron flow than tungsten
lower
45
According to Ohm's law, _______
I=V/R
46
The symbol for ohm is _______
omega (upside down horseshoe)
47
In the equation I=V/R, I is expressed in __________
amperes
48
In the equation I=V/R, V is expressed in ________
volts
49
THe _________ terminal of a dry cell identifies the location of the carbon rod
positive
50
A wire with a resistance of 3 Ohms has a _________ resistance to electron flow than a wire with a resistance of 5 ohms
lesser
51
If two copper wires are the same length, but different thicknesses, the _________ wire has greater resistance
thinner
52
What are the two types of circuits?
Parallel | Series
53
Definition of: series circuit parallel circuit
Series circuit: The current has only one loop to flow through. parallel circuit: The current has more than one branch.
54
Too many appliances in a circuit can cause a
fire | insulation to melt
55
For protection, household circuits contain
fuses that melt a wire and open the circuit | circuit breakers the switch flips and the circuit is open
56
Definition of electrical power
Rate at which electrical energy is converted to another form of energy
57
``` Unit of electrical power: Name- Abbreviation- Term for 1,000 units- Abbreviation for 1,000 units- ```
Watt W Kilowatt KW
58
Determining the electrical power of a circuit: Expression- Formula-
Power = current X voltage | P=IV
59
A power rating lists the ___________ required to operate an appliance.
watts
60
A closed path through which electrons can flow is _______
a circuit
61
A fuse will melt if the _________ in a circuit becomes too high
current
62
Current is almost always the flow of ________
electrons
63
A current has two or more branches in a ___________
parallel circuit
64
A car battery is an example of a ________
wet cell
65
The tendency for a material to oppose the flow of electrons is called _________
resistance
66
Current has only one loop to flow through in a ________
series circuit
67
Current is measured in _________
amperes
68
Electrical energy is equal to _________ X time
power
69
Electrical power is equal to __________ X voltage difference
current
70
Ohm's law states that the current equals _______ divided by the resistance
voltage difference
71
A dry cell is used in a flashlight to convert ________ to light
electrical energy
72
Thin wires have a ___________ resistance to electron flow than thicker wire do
greater
73
One thousand watts of power used in 60 minutes is _______
1 kilowatt-hour
74
What are the 4 necessities for a circuit?
1. Power Source (battery - pushes electrons) 2. wires "conductor" 3. device (like a light bulb) 4. switch (on and off)
75
Define insulator
Something that electricity does not move through easily
76
Define conductor
Something that electricity does move through easily
77
Define series
A circuit with only one path
78
What are some insulators?
Clothes | Shoe laces
79
What are some conductors?
Earring Ring Copper wire lead on a pencil
80
Define parallel
A circuit with two or more branches
81
A measure of the amount of energy used to move 1 coulomb of electrons
voltage
82
a complete path through which a current travels
electric circuit
83
a measure of how difficult it is for an electric current to flow through a material
electric resistance
84
The unit used to measure electric resistance is the
ohm
85
Describe the relationship between electric resistance and the flow of electric current in materials
Good conductors have low resistance
86
What type of copper wire has low resistance
short, thick wire
87
If the current and resistance in a circuit are known, the voltage can be determined by
multiplying the current and resistance
88
How to determine the amount of voltage each device is getting in a circuit
Divide the voltage by the number of devices
89
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
V=IR V=0.25(28) V= 12 12 Volts
90
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?
V=IR V=3(40) V=120 120 Volts
91
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?
V=IR V=0.1(40) V=4 4 Volts
92
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.
V=IR V= 0.06(50,000) V= 3,000 3,000 Volts

Physical Science 8 (1 decks)

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