AcaDec_1920s > Science Section 2 > Flashcards

Science Section 2 Flashcards

(141 cards)

Study These Flashcards
1
Q

Why can air normally act as an insulator between two charged objects, and what physical limit determines when it breaks down?

A

Air resists current flow until the electric field exceeds its dielectric strength

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How does dielectric breakdown in a thunderstorm compare to that in a capacitor?

A

Both involve charge buildup across an insulating medium (air between cloud and ground or plates) until breakdown allows a sudden discharge, neutralizing both sides

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Why do capacitors in electronics often use plastic or paper instead of air as the dielectric?

A

These materials have higher dielectric strength, allowing more charge storage before breakdown occurs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What process causes a shock when touching a doorknob on a dry day, and how is it analogous to lightning?

A

The air between hand and knob breaks down once the field is high enough, creating a miniature current burst—like a small-scale lightning discharge

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

In what way do a storm cloud and the ground behave like the two plates of a capacitor?

A

The negatively charged cloud base and positively charged ground form opposite plates separated by insulating air until breakdown (lightning) occurs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Why is a lightning bolt visible even though electrons themselves cannot be seen?

A

The air heats and glows from the energy of the current, similar to a lightbulb filament’s glow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What produces thunder immediately after a lightning strike?

A

A sonic boom from rapid air expansion as lightning superheats air to temperatures hotter than the Sun’s surface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Explain how crouching close to the ground during a lightning storm reduces your risk of being struck.

A

It minimizes potential difference between your body and ground, lowering the current that could pass through you if lightning strikes nearby

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Why should people avoid holding metal objects like umbrellas during lightning storms?

A

Metal provides a path of low resistance for charge, increasing the risk of a lightning strike through the person

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How does the Earth’s electric field relate to frequent lightning strikes worldwide?

A

Constant charge separation within storms creates a global electric field, making Earth act as one giant capacitor with continual discharges

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are transient luminous events (TLEs), and how do they relate to lightning?

A

TLEs—such as sprites, elves, and jets—are brief discharges above storm clouds, resulting from storm-induced charge separation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Why are TLEs rarely observed despite their frequency?

A

They occur high in the atmosphere where air is thin, producing dim, short-lived flashes often visible only with sensitive cameras

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Describe the energy transformation occurring during lightning.

A

Electrical potential energy from separated charges converts to thermal, light, and sound energy during discharge

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What property of a dielectric determines its ability to prevent breakdown, and how does it influence capacitor design?

A

Its dielectric strength—materials with higher strength permit higher voltages and greater energy storage before failure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Why might a car be a relatively safe place during a lightning storm?

A

The car’s metal frame conducts charge around passengers, acting as a Faraday cage that keeps interior electric fields low

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What early device was used to store electric charge before batteries existed?

A

The Leyden jar, which functioned as an early form of capacitor.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How did a Leyden jar work?

A

Charge built up on the inner foil attracted opposite charges on the outer foil, creating stored electrical energy.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What happens when a capacitor is connected to a battery?

A

It accumulates the same voltage as the battery after a while.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What makes a capacitor different from a battery?

A

A capacitor cannot maintain its voltage once current is allowed to flow between its ends.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What happens if you connect the two ends of a charged capacitor with a wire?

A

The separated charges neutralize each other, and the capacitor loses its charge.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are capacitors commonly used for?

A

For providing a quick, temporary flow of current, such as in a camera flash or RAM storage.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Why can capacitors be dangerous even when a device is unplugged?

A

They can store energy that may still discharge through you.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What determines how much charge a capacitor can store?

A

Its capacitance, which depends on the size and distance of its conductors.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

How does a computer keyboard key use capacitance?

A

Pressing a key moves two metal plates closer together, changing the capacitance and sending a signal.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
How is a capacitor represented in a circuit diagram?
By two parallel lines of equal length, showing that either end can become positive or negative.
26
What happens when a capacitor is charging in a circuit?
Current flows into it until the voltage across the capacitor equals the battery voltage.
27
What happens when the capacitor is disconnected from the battery?
Current temporarily flows within the circuit as the capacitor discharges and neutralizes itself.
28
What is a dielectric?
A material placed between the capacitor’s plates that increases how much charge it can store.
29
How does a dielectric increase a capacitor’s ability to store charge?
The dielectric polarizes, creating an electric field opposite to the capacitor’s, reducing discharge and allowing more charge storage.
30
What is created when two resistors are in parallel.
A parallel circuit.
31
What happens if two resistors have the same resistance?
The same amount of current flows both ways.
32
What happens if two resistors have a different resistance?
More current will flow through the resistor with lower resistance.
33
What happens to the current of three lightbulbs connected in parallel?
The current branches off and travels through the different bulbs independetly.
34
What does connecting 3 resistors do?
Increase resistance and decrease the current.
35
What is a fuse?
A bit of wire made of a different material than the rest of the wiring.
36
What are fuses made of?
A material that has a low melting point and through which all current from outside must flow to get inside.
37
What happens to a fuse when a current is too high?
The fuse melts, which shuts off current from reaching anywhere inside your home, so you have to replace the fuse.
38
What is a circuit breaker and what does it do?
A piece of metal that if heated too much, will expand in such a way that it breakes the circuit, and current will not be able to flow until it cools down again.
39
What do the two prongs of a typical plug represent?
The high and low voltages that lead to current flow.
40
What do three prong plugs do?
It is directly connected to the ground, so that if the appliance itself becomes charged due to a loose wire, the current will tend to flow through the prong rather than anyone who touches the appliance.
41
What is a capacitor?
Any two conductors seperated by some small distance.
42
Why is voltage sometimes referred to as "electric pressure"?
This is because like pressure, voltage is not something that flows, it is a measured quantity at two ends of a circuit (pipe for pressure).
43
Why is voltage sometimes referred to as "electromotive force" (EMF)?
Even though it is not really a force, neither is the height from which an object falls. The force would be gravity. The reason we call it EMF is because voltage is a quantity that we can measure that tells us how powerful the circuit will be.
44
What is Newtons third law of motion
That when an object exerts a force onto another object it feels and equielent force back on it
45
when two balls of equal mass collide what happen to the energy in the system
The energy gets transferred from the ball being moved to the ball being hit
46
when one ball that is moving collides with a stationary ball of the same mass what happens to the energy in the system
The speed of the ball that was moving drops to zero while the stationary ball starts moving in the direction that it was hit with the same speed
47
What is absolute zero
The temperature where no atoms are moving at all
48
What is the third law of thermodynamics
No substance will ever fully reach the temperature of absolute zero4
49
When will a pendulum be at maximum Potential energy and minimize Kinetic energy
At the peak of the swing
50
When will a pendulum be at minimum uses the Potential energy and maximum Kinetic energy
At the bottpm of its swing
51
What is the byproduct that is released when something slows down due to friction
heat
52
What energy can readily be turned into Kinetic energy
Potential energy
53
What is the energy that an object have if it is high up
Potential energy
54
How does voltage refer to electric potential
voltage is the difference in electric potential
55
What unit measures voltage
volts, or joules per coulomb
56
What happens when two objects with different temperatures interact?
The higher-temperatures "flow" into the lower-temperature as the atoms collide with each other, passing their energy to each other. Heat is the combined kinetic energy exchange between all atoms.
57
During the industrial revolution, a teenager who worked at a family brewery in England proposed a very very important connection. Who was it, and what was the connection?
A young James Joule, who proposed that the work a motor does and the heat it produces are connected when he tinkered with electric motors.
58
Joules are used to measure what quantity?
Energy, such as potential, kinetic, mechanical, heat, etc.
59
Lord Kelvin, or William Thomas, created was set of laws to verify James Joule's proposal of work and heat being connected.
The Laws of Thermodynamics, which states things such as the conservation of energy.
60
How did James Joule experiment to prove correlation between energy and heat using a block and a jug of water?
He, in one of his experiments, allowed a block to fall while tethered to a rope that connects to paddles in a jug of water, and that gives the "lost" energy to the water via warming it very slightly.
61
What can be said with the amount of joules of energy in a closed system, such as the universe?
They will ALWAYS stay the same, as energy cannot be created nor destroyed.
62
If you are moving forward by walking, what type of energy are you utilizing?
Kinetic energy, which is simply energy everything has only when they are moving.
63
Energy transferring from heat energy to nuclear energy to light energy and then finally kinetic energy is the path of energy for everything you do, why is that?
Because when you act, you require kinetic energy, which you got from eating food, which ultimately got it's energy from the bottom of the food chain, which got it's light from the sun, which got it's energy from nuclear fusion, which got it's energy from the beginning of the universe.
64
Where might energy exerted into throwing a ball onto the ground go to?
Sound energy, creating the 'thud' noise, into the ground, sending tiny vibrations, and into the ball itself, compressing itself ever-so-slightly.
65
Two objects, differentiating in temperature, interacting begin what transit of energy?
Heat, however no objects contain heat itself, rather merely emit and absorb heat.
66
What might scientists before the late 1700s refer to what we now know as heat transfer as?
Phlogiston, which was believed to be it's own seperate substance before experiments in combustion disproved that theory.
67
Temperature typically describes what?
The average kinetic energy of the atoms in a substance, with the hotter temperatures being faster movements.
68
How does the movement of atoms within a solid and a liquid substance change?
In a solid, atoms vibrate in place, but in a liquid the atoms freely move around.
69
Who are volts named after
Alessandro Volta
70
What is a battery in millitary contexts?
a coordinated group of military weapons
71
early on, batterieswere simpily called what?
piles
72
The origin of the battery started when what dead animal jolted after being touched with 2 metals?
a frog
73
Which pair of married scientists started the discussion on wether electricity was the "Mysterious Lfe Force"
Luica & Luigi Galvani
74
The Galvani's belived that in their experiment, the animal contained the electricity. Volta belived that the ____ contained the electricity
metal rods
75
Alessandro Volta proved hos theory on the Galvani's experiment by using _____ instead of dead animals
soaked cardboard
76
What inside of the frog caused the animal to jolt when pronged with 2 metal rods
the acid, it dissolved the metal & 'stole' electrons
77
Allasandro Volta showed his battery to what famous 17th century french-men
Nepoleon
78
Who first showed that the left hemisphere controls the right side of your body & vise versa
Giovani Aldini
79
Modern disposabe batteries Use 2 rods of _____ & _____ submirged in _____
zinc & carbon, submerged in suferic acid
80
In a disposable battery, if you connect the + & - rods, what happens?
the - charge neutralizes the + charge, & the acid repenishes the charges of the rods
81
you can make your own disbosabe battery by dipping 2 metals in...
a lemon or lime
82
What are disposable, one-use batteries also known as?
primary cells
83
What are secondary cells?
batteries that can be recharged
84
What type of batteries do many devices use today?
lithium-ion batteries
85
How do lithium-ion batteries work/in what direction do the lithium ions move?
lithium-ion batteries move ions of the element lithium through a conduction chemical fluid
86
How are lithium-ion batteries able to be reused? (Hint: it has something to do with the movement of lithium ions)
when the battery is charging, the terminals are switched, so the lithium ions move back from the conducting chemical fluid to the other side
87
True or False? Rechargeable betteries can be used forever
88
What type of batteries do most portable devices use today?
lithium-ion batteries
89
What is generated through friction as lithium ions move back and forth in the lithium-ion battery? And where is it transferred?
heat is gradually transferred to the cooler surroundings
90
Why aren't rechareable batteries able to be used forever?
because energy is permanently taken away from the battery as the heat generated through friction by the movement of the lithium ions is transferred to cooler surroundings
91
What can happen if too much heat is generated from a battery?
the battery can catch fire as the chemicals are flammable
92
True or False? It is rare for lithium-ion batteries to catch on fire
t
93
What is a circuit?
a closed loop that allows electricity to continually flow
94
All types of fluid prefer to flow from areas of _____ pressure to ______ pressure
high, low
95
True or False? Air is a type of fluid
t
96
What is the purpose of a battery? What does this create?
it is to keep charge separated on each end, which creates a potential difference
97
What happens if the positive charge of the battery flows into a region of negative charge?
the negativity would be neutralized, and eventually the charge will balance out, and no current flow
98
What is direct current?
current that always flows in the same direction
99
What happens when a wire connects the positive and negative ends of a battery?
it provides a conductive path for charges to move, allowing current to flow through the circuit
100
Why is metal used for wires in electrical circuits?
because they are great conductors
101
In the water pump analogy, why does water stop flowing after one squeeze of the pump, and how does it relate to electric current?
without any continuous pumping, friction slows the water to a stop. This is similar to a battery if it stops maintaining potential difference, the charges will balance out so not current will flow
102
In the playground slide analogy, what role does the battery play?
the battery is analogous to a person lifting a child back to the top, supplying energy to maintain continuous motion (current)
103
What is a real-world phenemon we see daily that also depends on movement from high to low pressure, like charge flow in a circuit?
weather patterns
104
When it comes to electric forces, do protons or electrons move more?
Electrons move more, since protons hardly move in comparison.
105
What was Benjamin Franklin's mistake when describing his "electrical fire"?
He was wrong about which way the charge was flowing between objects.We discovered that the particles that actually move in electrical phenomena are those that Franklin referred to as having negative charge.
106
What is the number of amps needed to cause a slight shock on a person?
0.001 amps
107
What is the number of amps needed to cause a painful shock on a person?
0.005 amps
108
What is the number of amps needed to cause a lossof muscle control on a person?
0.015 amps
109
What is the number of amps needed to cause a shock that is potentially fatal to a person?
0.070 amps
110
What does the word electrocution come from?
Electrocution is a portmanteau of "electricity" and "execution", it refers to killing someone with electricity
111
How how is a lightning bolt?
It is hotter than the surface of the sun
112
How does a person's internal organs communicate with eachother?
Through electric force
113
What is a electrocardiogram?
A device that measures voltage across various parts of the body to measure a person's heartbeat.
114
What does voltage create the conditions for?
Voltage creates the conditions for current to flow.
115
What actually affects you—voltage or current?
Current affects you; it’s the actual flow of charge.
116
Why are high voltages not always dangerous?
Because without a conductor for current to flow through, no charge moves—even at high voltage.
117
What does voltage always refer to?
A potential difference between two points.
118
What is the best rule of thumb when dealing with electronics?
Don’t tamper with electrical devices unless you are an expert.
119
What is the physics definition of power?
Power is the rate of energy change over time.
120
What is the unit of power, and what does it equal?
The watt (W) — equal to one joule per second.
121
How much energy does a 100-watt lightbulb convert per second?
100 joules of electrical energy into 100 joules of light and heat per second.
122
Why do wires heat up when current flows through them?
Because of resistance—some electrical energy is converted to heat energy.
123
Why are household wires covered in insulation?
To protect from heat and prevent electrical contact.
124
Why does a tungsten filament glow in a lightbulb?
High current heats it to about 2,000°C, making it glow.
125
What is a kilowatt-hour equivalent to in joules?
3,600,000 joules (3.6 million J).
126
Are the electrons in your lamp coming directly from the power plant?
No—the electrons are already in your home’s wires.
127
What happens when you flip a light switch on?
A signal (electric field) travels from the power plant, causing electrons in your wires to start moving.
128
What analogy explains how energy travels through wires?
The domino analogy—the energy (not the electrons themselves) transfers quickly through the line.
129
What causes the temperature of a wire to increase when current flows through it?
protons in the wire jiggle more (not as much as the electrons, though)
130
True or False? Protons in a wire move less compared to electrons during current flow
t
131
True or False? A lower-temperature object’s atoms are jiggling around at faster speed compared to a high-temperature object
False; the atoms will actually be moving more slowly
132
How does increasing temperature affect the resistance of a wire?
resistance will also increase
133
Why is resistance higher when temperature increases?
because the faster atomic vibrations (result of an increase in temperature) interfere with the flow of electrons
134
True or False? Substances with low temperatures will have higher resistance
False; they will have lower resistance because resistance is directly proportional to temperature (meaning it decreases with temperature)
135
What are superconductors?
a material with zero resistance; only possible at extremely low temperatures
136
What type of machines are superconductors currently used in?
machines that require high currents, such as MRI machines and particle accelerators
137
What do physicists hope to use superconductors for?
to send ordinary electricity to homes across cities
138
Why don’t we use superconductors to send ordinary electricity to homes across cities?
because they are very expensive and impractical for everyday use as the only superconducting material we know of requires extremely low temperatures
139
In a circuit diagram, what do two small parallel lines represent?
the battery
140
In a circuit diagram, if the two parallel lines represent the battery, how do we know the charge of each terminal?
the positive side is represented by a longer line, while the negative side is represented by a shorter line
141
In a circuit diagram, how is a resistor represented?
AcaDec_1920s
flashcards
Decks in class (24)
# Cards
Brainscape helps you reach your goals faster, through stronger study habits.
© 2026 Bold Learning Solutions. Terms and Conditions