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Science 9 > Unit 4: Electricity > Flashcards

Unit 4: Electricity Flashcards

1
Q

What is static electricity?

A

Stationary electricity

Atoms are neutral, (Same # of protons and electrons)

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1
Q

What is Charge Seperation

A

When charged objects are brought near neutral objects. May cause neutral object to become attracted to charged object

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2
Q

What is electrical Discharge

A

When a built up charge is attracted to another object and jumps to it. Usually felt as a shock

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3
Q

what is the Van De Graaff Generators

A
  • builds static electricity
    How it works
  • rubber belt rubs on metal
  • Transfers charge to sphere where it builds up
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4
Q

What is Current electricity

A
  • steady flow of charged particles
  • keeps flowing until source runs out or it cut off
  • Conduction occurs through wires in contact
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5
Q

What are free electrons

A
  • electrons separated from out shell

- carry current of electricity in wires

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6
Q

what are the conditions for an electric current

A
  • energy source

- complete path for circuit

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7
Q

What is a circuit

A
  • paths that control the flow of electricity
  • typically use solid metal

Includes - conductor, energy source, load

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8
Q

What is a conductor

A
  • rapid flow of electrons in material
    Ex. Metalic - copper
    Non-metallic - carbon, graphite, water solutions of salt, acids, alkalis
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9
Q

What are insulators

A

Material resists flow of electrons/ doesn’t allow electrons to flow easily (also called resistors)
Ex. wood, rubber, fabric, Tungsten, Nichrome

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10
Q

What are Amperes

A

The rate at which an electrical current flow is measured

- Named after French physicist, mathematician, philosopher Andre-Marie Ampere

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11
Q

What devices can e used to measure current

A

Galvanometer - weak currents

Ammeter - strong currents

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12
Q

What is Voltage

A
  • Electrical energy carried by charged particles
  • How much energy each particle charged particle has
  • Higher voltage = higher potential energy
  • “Potential difference”
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13
Q

how do you measure Voltage

A
  • Volts
  • Alessandro Volta, Italian physicist
  • Voltmeter
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13
Q

how do you measure Voltage

A
  • Volts
  • Alessandro Volta, Italian physicist
  • Voltmeter
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14
Q

What is more deadly, Voltage or Current

A

Current

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15
Q

What are Fuses

A

Thin metal that melts with too much current

Must be replaced

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16
Q

What are Circuit breakers

A
  • wire that triggers spring mechanism that turns off switch when too hot
  • can be reset
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17
Q

What are electrochemical cells

A
  • cells that use chemical reactions to create electricity

- irreversible reaction

18
Q

What are Dry Cells

A
  • cans full of chemicals that produce electrons
  • Chemicals that react are in a paste
  • Sealed with asphalt
  • made in zinc container also functions as negative pole
  • Cell works as long as the paste is moist
19
Q

What are cell terminals

A
  • cells have two terminals, pos and neg

- electrons flow from neg (zinc) to pos (carbon)

20
Q

What are wet cells

A
  • use liquid electrolyte (acid) instead of a paste
  • cheaper than wet cells, but wear out faster
    ex. car batteries
21
Q

What are the parts of the a wet cell

A
  1. effective electrolyte
  2. two electrodes (one pos and one neg)
  3. Wires connecting terminals
22
Q

What is electrochemistry

A

electrolysis - using electricity to separate useful elements

electroplating - using electricity to coat cheaper metals with expensive metals

23
What are superconductors
- almost perfect conductors - almost no resistance electron flow - discovered by dutch physicist Heike Kamerlingh Onnes in 1911
24
How are resistors used in appliances
- resistors limit the amount of current | Ex. toasters use high resistance wire to convert the electricity into light and heat
25
what is resistance
a measure of how difficult it is for electrons to flow through a substance The more resistance a substance has, the more the substance gains energy from each electron that passes through it Solutions can also be resistors - more charged particles = low resistance - Fewer charged particles = high resistance
26
What types of resistors are there
1. wire round - made of heat resistant alloy wrapped around an insulating core (longer and thinner = high resistance) 2. carbon-composition - made of carbon mixed with other materials
27
What tools are used to measure voltage and amperes
Voltmeters - measuring small voltages (millivoltmeters) Ammeters - measure current Galvanometers - measure small currents Multimeters - measure voltage, current and resistance is a circuit
28
What are the main parts of a circuit drawing
1. Power source 2. Conductor 3. Load 4. Switching mechanism
29
What is the difference between a parallel and series circuit
Parallel - two or more paths, if one load malfunctions the others, there is still a path from pos to neg Series - all the loads are in a row, one path for electricity, more loads = dimmer light
30
What are combination circuits
- has a combination of series and parallel paths | - parallel section is part of a series circuit
31
What is energy
the ability to do work
32
What types of energy are there
Chemical – released when chemicals react Mechanical – energy an object has because of motion or the ability to move Electrical – energy of charged particles Thermal – total kinetic energy of particles in a substance
33
What is the law of conservation of energy
"Energy is neither created nor destroyed, it just changes form"
33
What is the law of conservation of energy
"Energy is neither created nor destroyed, it just changes form"
34
What is a thermocouple
- a device that converts thermal energy to electrical energy | - consists of two different metals that conduct heat at different rates
35
What is are electromagnets
Permanent Magnets - always magnetized, (bar magnets, horseshoe magnets) Electromagnets - only magnetized when there's a current (Scrap metal cranes)
36
What are the parts of an electric motor
- Armature or rotor (electromagnet) - Commutator - Brushes - Axle - Field magnet - Power supply
37
How does a Motor work
- uses magnets to create motion - magnet poles attract and repel - The attracting and repelling forces create rotational motion
38
What are the two types of magnets in a motor
Electromagnet - armature/rotor | Field magnet /permanent magnet
39
What are the two different types of currents
AC - alternating current, flows back and forth 60 times per sec DC - direct current, only flows in one dirrection
40
What is electromagnetic induction
moving a coil of wire through a magnetic field generate a steady supply of electricity
41
What is power
- the rate at which a device converts energy from one form to another - the unit is watts - 1 watt = one joule/second
42
What is energy
- The ability to do work | - measured in joules
43
What lowers the efficiency of a machine
- Input energy is often converted to “waste” energy such as heat - In devices that convert electricity to mechanical energy, friction is responsible for creating a lot of waste energy.
44
How can you increase efficiency
- better bearings - use lubricants - improve insulation

Science 9 (5 decks)

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