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Science 9 > Unit 4: Electricity > Flashcards

Unit 4: Electricity Flashcards

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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
Q

What are superconductors

A
  • almost perfect conductors
  • almost no resistance electron flow
  • discovered by dutch physicist Heike Kamerlingh Onnes in 1911
24
Q

How are resistors used in appliances

A
  • resistors limit the amount of current

Ex. toasters use high resistance wire to convert the electricity into light and heat

25
Q

what is resistance

A

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
Q

What types of resistors are there

A
  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
Q

What tools are used to measure voltage and amperes

A

Voltmeters - measuring small voltages (millivoltmeters)
Ammeters - measure current
Galvanometers - measure small currents
Multimeters - measure voltage, current and resistance is a circuit

28
Q

What are the main parts of a circuit drawing

A
  1. Power source
  2. Conductor
  3. Load
  4. Switching mechanism
29
Q

What is the difference between a parallel and series circuit

A

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
Q

What are combination circuits

A
  • has a combination of series and parallel paths

- parallel section is part of a series circuit

31
Q

What is energy

A

the ability to do work

32
Q

What types of energy are there

A

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
Q

What is the law of conservation of energy

A

“Energy is neither created nor destroyed, it just changes form”

33
Q

What is the law of conservation of energy

A

“Energy is neither created nor destroyed, it just changes form”

34
Q

What is a thermocouple

A
  • a device that converts thermal energy to electrical energy

- consists of two different metals that conduct heat at different rates

35
Q

What is are electromagnets

A

Permanent Magnets - always magnetized, (bar magnets, horseshoe magnets)

Electromagnets - only magnetized when there’s a current (Scrap metal cranes)

36
Q

What are the parts of an electric motor

A
  • Armature or rotor (electromagnet)
  • Commutator
  • Brushes
  • Axle
  • Field magnet
  • Power supply
37
Q

How does a Motor work

A
  • uses magnets to create motion
  • magnet poles attract and repel
  • The attracting and repelling forces create rotational motion
38
Q

What are the two types of magnets in a motor

A

Electromagnet - armature/rotor

Field magnet /permanent magnet

39
Q

What are the two different types of currents

A

AC - alternating current, flows back and forth 60 times per sec

DC - direct current, only flows in one dirrection

40
Q

What is electromagnetic induction

A

moving a coil of wire through a magnetic field generate a steady supply of electricity

41
Q

What is power

A
  • the rate at which a device converts energy from one form to another
  • the unit is watts
  • 1 watt = one joule/second
42
Q

What is energy

A
  • The ability to do work

- measured in joules

43
Q

What lowers the efficiency of a machine

A
  • 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
Q

How can you increase efficiency

A
  • better bearings
  • use lubricants
  • improve insulation

Science 9 (5 decks)

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