Electricity Unit Flashcards
1
Q
What is static electricity?
A
A stationary Electric charge.
2
Q
What is a proton?
A
A positively charged particle in the nucleus of an atom.
3
Q
What is an electron?
A
An invisible negatively charged particle that orbits the nucleus of an atom.
4
Q
What is a neutral charge?
A
Description of an object that has equal amounts of positive and negative charges.
5
Q
What is charge separation?
A
Concentration of like charges in specific area of a neutral object, caused by the approach of a charged object; for example, a negatively charged object brought close to a wall repels the electrons in the wall, leaving the area of the wall closest to the object positively charged.
6
Q
What is electrical discharge?
A
A sudden transfer of electrical charge from one object to another, indicated by a spark.
7
Q
What are the laws of electrical charges?
A
Opposite charges attract each other and like charges repel each others.
8
Q
What is electrical current?
A
A steady flow of charged particles.
9
Q
What is amperes?
A
Ampere (A) is the unit of electrical current.
10
Q
What is a conductor?
A
A material that electric charge can more through easily.
11
Q
What is a circuit.
A
Is the complete path that charged particles flow through. Is a path that controls the flow of electricity.
12
Q
What is a load?
A
Is a device to convert electrical energy to another form of energy. For example, a light bulb is a load, it converts electrical energy to light and heat.
13
Q
What is electrical energy?
A
The energy carried by charged particles.
14
Q
What is voltage?
A
Is a measure of how much electrical energy each charged particle carries.
15
Q
The higher the voltage is, the _____ the potential energy of each particle?
A
Greater
16
Q
What else is voltage called?
A
Potential difference
17
Q
What is potential difference?
A
Change in the potential energy of electric charge compared to its potential energy at a reference point, such as the ground; voltage.
18
Q
The energy delivered by a flow of charged particles is _____ to the voltage ______ the total charge of the electrons.
A
equal; times
19
Q
What is the unit of voltage?
A
volt (v)
20
Q
What do you use to measure voltage?
A
A voltmeter
21
Q
What is a short circuit?
A
Is an accidental low-resistance connection between two points in a circuit, often causing excess current to flow.
22
Q
Without a ______ circuit, electricity can not flow.
A
Complete
23
Q
True or false: electricity can find another path, such as through a person’s body to the ground, when there is not a complete circuit.
A
True
24
Q
Is amps to volts more important to consider when assessing the potential danger of an electrical shock?
A
Amps
25
If you are in a car with a power line touching the vehicle, how should you exit the car, why?
You need to jump, not step out. Stepping to the ground would provide a path for the electricity to flow through to the ground.
26
What are insulators?
A substance that strongly resists the flow of electricity.
27
What are examples of insulators?
Wood, rubber, and air.
28
What is are fuses?
A thin piece of metal that melts to break an electrical circuit when excess current flow occurs
29
What are circuit breakers?
A special wire that heats up and turns off switch when excess current flows through an electrical circuit.
30
What kind of cell foes the electricity used to operate a pacemaker come from?
Electrochemical cells
31
What is an electrochemical cell?
A package of chemicals designed to produce small amounts of electricity; produces electricity from chemical reactions.
32
Explain the difference between a dry cell and a wet cell.
The chemicals in a dry cell are like a past, where as a wet cell uses a liquid electrolyte that is usually an acid.
33
What is an electrolyte?
A liquid or past that conducts electricity because it contains ions.
34
What is an ion?
An atom that have become electrically charged because it has gained or lost electrons.
35
What are electrodes?
A conductor through which electric current enters or leaves a device or material.
36
Are car batteries made up of wet or dry cells?
Wet cells.
37
What is a primary cell?
Dry and wet cells that produce electricity from chemical reactions that cannot be reversed.
38
What is a rechargeable cell?
Cells where the chemical reactions can be reversed by using an external electrical source to run electricity back through the cell.
39
What are secondary cells?
A rechargeable cells.
40
What is a battery?
A set of cells connected together
41
What is electrolysis?
The decomposition of a substance by any electric current.
"Other scientists had earlier used smaller batteries to split molecules into their elements, a process called electrolysis" (pg 292)
"Many industrial processes use electrolysis to separate useful elements from solutions." (pg 293)
42
What is electrochemistry?
The study of chemical reactions involving chemistry.
43
What is electroplating?
Is the use of electricity to coat a thin layer of metal onto an object.
44
What makes neon signs a unique circuit?
"Neon signs usually consist of a glass tube, twisted into the desired shape. The tube is filled with gas and metal terminals are sealed into the ends. The metal terminal of the tube are then connected to the positive and negative terminals of the electrical source. So the sign is a circuit, but unlike wire circuits, the circuit in neon signs includes a gas as a conductor." (pg 297)
45
What are examples of conductors?
Metals such as silver, copper, mercury, and gold.
46
What are superconductors?
A perfect conductor; substance with no resistance to electron flow.
47
What is a resistor?
A device having resistance to the passage of electrical current, often used to control current in a circuit.
48
What is resistance?
The measure of how difficult it is for electrons to flow through a substance.
49
What is ohms?
The unit of resistance
50
The _________ charged particles in a solution, the better it conducts.
More
51
What is the best method for turning electricity on and off in a circuit?
A switch
52
What happens when a switch is on? When a switch is off?
When a switch is on, two conductors are pressed together so that current can flow from one to the other.
When a switch is off, the conductors are separated and no current flows.
53
What is a variable resistor or rheostat?
A resistor whose resistance can be changed by adjusting the portion of the resistor that current travels through. A continuously variable resistor used to regulate electric current.
Rheostats can increase or decrease the amount of current in a circuit.
For example, a light switch in that is used to dim the lights.
54
How is flowing water like the flow of electricity?
Since electrons "flow" through conductors and resistors, a model using water best represents electricity.
Like flowing water, electricity must come from a source. Like water smashing into rocks in rapids, electricity encounters resistance. The more water, the more powerful the current in a river. The more electrons, the more powerful the current is in a conductor. For both water and electricity, the source must be constantly replenished for the flow to continue. If there is no water the flow would stop. If a generator is shut down or when the cell is used up, the electricity stops flowing.
55
How does water flow/waterfalls model voltage?
Unless there is a change in elevation, water doesn't flow - it simply sits in a pool. If you pump water up a hill, it gains gravitational potential energy, and then flows back down. In a similar way, a cell, batter, or generator "pumps" electrons to a point with a higher electric potential (voltage). Electricity will not flow without a difference in electrical potential, just as water does not flow without a difference in gravitational potential energy. The higher and greater the amount of water the greater the flow of water. Similarly, the high-voltage electrons from a generating station have more electrical potential energy than low-voltage electrons from a flashlight battery.
56
How does water flow in a pipe model resistance and current?
The flow of water in pipes is another useful way to understand electricity. Suppose you were using a reservoir to provide irrigation water for a field. You have to decide what size of pipes to use to drain the reservoir. A pipe with a small diameter might be easier to hook up. However, the longer and thinner a pipe is, the more resistance it has to the flow of water. A pipe with a bigger diameter has less resistance, which allows a greater flow of water. Similarly, the amount of resistance in a circuit affects the electrical current. For any given voltage, current decreases if you add resistance. As with water, you get the least resistance with a short, wide path with no obstructions. The shorter and thicker the wire, the less resistance it creates for electrons. The flow of current will be reduced if it has to pass through a resistor.
57
Ohm's law states that as long as the temperature stays the same:
The resistance of a conductor stays constant and the current is directly proportional to the voltage applied.
In other words, if you increase the voltage in a circuit, the current also increases.
If the voltage stays the same, but a resistor of greater value is used, then the current decreases.
58
What is a series circuit? What are the disadvantages of a series circuit?
In a series circuit, there is only one pathway for the current.
Disadvantages:
If that pathway is interrupted, the whole circuit cannot function.
Adding components increases the total resistance of the circuit. This decreases the current. For example, adding an extra bulb to a series sting of lights make all the bulbs dimmer.
59
What is a parallel circuit?
What is a parallel circuit? Parallel circuits have a separate current path for each section of the circuit.
An interruption or break in one pathway does not affect the rest of the pathways in the circuit.
60
Does adding extra resistors in a parallel circuit increase or decrease the total resistance of the circuit.
It decreases the total resistance.
Adding more paths for the current to take means less total resistance. (think about how much less resistance there is when you drink through two straws instead of one.)
61
What is energy?
The ability to do work
62
What is chemical energy?
The energy stored in chemicals. This is a form of potential or stored energy. This energy is released when chemicals react.
The energy that is found in chemicals.
63
What is electrical energy?
The energy of charged particles. Electrons are negatively charged. Electrical energy is transferred when electrons travel from place to place.
64
What is mechanical energy?
The energy possessed by an object because of its motion or its potential to move. A thrown baseball has mechanical energy because of its movement and its potential to fall.
65
What is thermal energy?
The total kinetic energy of all the particles in a substance. The faster a particle moves, the more kinetic energy it has.
66
What is a thermocouple?
Is a device that can convert thermal energy to electrical energy
67
What is an electromagnet?
A coil of insulated wire (usually wrapped around a soft iron core) that becomes a magnet when current flows through it.
68
What do many electric motors use a commutator and brushes for?
Many electric motors use a commutator and brushes to reverse the flow of electricity through the electromagnetic coil.
When the contact is broken so is the magnetic force. But the armature continues to spin because of its momentum. As a result of the spinning, the commutator reconnects with the brushes.
Commutator = Split ring in a motor that breaks the flow of electricity for a moment and then reverses the connection of the coil.
Brushes = Mechanism that makes electrical contact with the moving commutator in a motor.
Armature = Rotating shaft and coil in a motor or generator.
69
What are transformers?
A device that changes electricity at one voltage into electricity at a different voltage; a step-up transformer increases the voltage; a step-down transformer decreases the voltage.
70
What is electromagnetic induction?
The generation of electric current in a conductor by changing magnetic field.
71
What is power?
The rate at which a device converts energy. The unit of power is the watt (W). A watt is equal to one joule per second.
72
The faster a device converts energy, the _______ its power rating.
Greater
73
What is a kilowatt hour?
A commonly used unit of electrical energy, equal to a power consumption of 1000 W for one hour.
74
What is the law of conservation of energy?
Energy cannot be created or destroyed. Energy does not just appear or disappear. Energy can only be transformed from one form to another.
75
What is efficiency?
The ratio of the useful energy output to the total energy input in a device or system; usually given as a percent.
76
What makes a device more efficient?
The more input energy that a device converts into useable output energy, the more efficient the device is.
77
Can a device that convert electricity to other forms of energy have a 100% efficiency?
No, devices that convert electricity to other forms of energy can NEVER be 100% efficient.
Any sort of movement generates a certain amount of thermal energy (heat) that is not useful output.
78
What are fossil fuels?
Fuel formed from dead plants and animals; coal, oil, and natural gas
79
What is a turbine?
A machine that uses the flow of a fluid such as steam, water, or air to rotate a shaft.
80
What is nuclear fission?
Is the splitting of atoms, which transforms them into lighter elements and releases large amounts of energy.
81
What is geothermal energy?
Energy derived from the internal heat of Earth.
82
What is biomass?
Organic matter, such as food or agricultural waste, used as an energy source.
83
What is cogeneration?
Is the use of waste energy from a process for another purpose, such as heating or generating electricity.
"Some industrial processes, such as glass manufacturing, use very high temperature furnaces. The waste heat from the manufacturing process can be used to produce steam. This steam can then be used to drive a turbine to generate electricity. Fuel is burned in the manufacturing process to produce the heat in the first place, but no new fuel is needed to produce the electricity. Making double use of energy in this way is called cogeneration"
84
How does hydro-electric power work?
"About 20% of the world’s electricity is generated by hydro-electric power plants. These plants capture the energy of falling water. Some hydroelectric plants, like the ones at Niagara Falls, use the flow from a waterfall, but most use a dam built across a river to store water in a reservoir. Water is directed through a channel called a penstock to a large paddle-covered turbine. The rushing water spins the turbine, which is connected to a generator in the same way as a steam-driven turbine."
85
Explain tides as an alternative energy source.
"Moving water from tides can also power turbines that run generators.Tidal power stations operate rather simply. When the tide comes in, the water is trapped in a reservoir and then let out past turbines. There are not many tidal power stations in the world because of the difficulty of finding suitable locations. One is located in Nova Scotia at the mouth of the Annapolis River. It takes advantage of the large tides in the Bay of Fundy. Waves can be used to generate electricity too. In one type of wave power generating station, the up-and-down movement of the water drives a piston connected to a generator."
86
Explain wind as an alternative energy source.
"Wind energy can be harnessed to turn a shaft. For centuries, windmills used sails on the ends of shafts to provide power to grind grain and pump water. Modern windmills use more efficient designs with propeller shaped blades. The amount of electricity a single windmill can generate is limited, but a number of wind-powered generators can be connected together in “wind farms” to produce larger amounts of electrical energy."
87
What are fuel cells?
The primary cell that generates electricity directly from a chemical reaction with a fuel.
88
What are nonrenewable resources?
A resource, such as coal or natural gas, that cannot be replenished.
89
What are renewable resources?
A resource such as water or wind energy that is continually replenished and therefore can be used indefinitely.
90
What is fly ash?
Fine airborne ash produced by burning coal or other solid fuels.
91
What is sustainability?
Use of resources at a rate that can be maintained indefinitely without depleting the resources of harming the environment.
92
What are the benefits of electrical technologies?
- Improved standard of living
- Speed and convenience
- Electronic devices help us to complete a variety of tasks more quickly and efficiently, and give us more time for other activities.
93
What are the drawbacks of electrical technologies?
- More resources are needed to manufacture and operate devices.
- As technology progresses, it leaves behind obsolete devices that are normally discarded as waste.
- Some technology is to expensive for people and countries to adapt, which can result in isolation
