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Science Sem 2 Exams > Electric and Magnetic Fields > Flashcards

Electric and Magnetic Fields Flashcards

1
Q

What is Electromagnetism?

A

1 of the 4 basic forces that make up everything in the universe

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2
Q

What is a Magnet?

A

A metal or rock, usually with high Iron content

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3
Q

What does a Magnet do?

A

Create an invisible field of force around themselves.

This field attracts other magnets and certain metals

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4
Q

Where are Magnetic Field’s concentrated?

A

Around the ends of the magnet. These ends are called Poles.

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5
Q

How many Poles does each Magnet have?

A

2 - North and South Poles

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6
Q

What happens when two opposite poles are held near each other?

A

If the poles are opposite (north and south), you will feel an attraction between the magnets

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7
Q

What happens when two identical poles are held near each other?

A

If the poles are identical (north and north or south and south), you will feel the magnetsrepelling each other

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8
Q

What is an example of a material that is naturally magnetic?

A

Lodestone, a rock that is rich in iron, is one example

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9
Q

What is Magnetisation?

A

If you run a nonmagnetic iron nail through a magnetic field, you can turn it into a magnet. This process is called magnetization.

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10
Q

What are Magnetic Domains?

A

Tiny magnetic crystals. Inside magnetic materials. You can think of Domains as tiny little magnets inside a big magnet

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11
Q

What way are the Domains facing?

A

In a magnet, all the domains are lined up the same way.

In a non-magnetic material, the domains are not lined up and face all directions.

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12
Q

What happens when you break a magnet?

A

If you break a magnet in half, the domains are still all lined up. So each half is a magnet on its own. Each half will still have a north pole and a south pole.

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13
Q

What is a Temporary Magnet?

A

If you hang a paperclip from a magnet, the paperclip becomes weakly magnetized. The paperclip is only magnetised when in contact with the magnet, so it is called a temporary magnet.

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14
Q

How do you see a Magnetic Field?

A

You can see a magnetic field using iron filings. The tiny bits of iron line up in the shape of the magnetic field. Magnetic fields of attraction look different to magnetic fields of repulsion

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15
Q

What does M.R.I stand for?

A

Magnetic Resonance Imaging

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16
Q

What does a M.R.I do?

A

An M.R.I is used in hospitals to obtain highly detailed images of a person’s insides.

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17
Q

How does a M.R.I work?

A

The patient’s body is placed in a powerful magnetic field and scanned by radio waves.

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18
Q

Does Earth have a Magnet?

A

Earth is a giant magnet. That’s because the planet’s core consists mostly of iron.

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19
Q

What is a Magnetosphere?

A

Earth’s Magnetic field that stretches out and around the planet.

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20
Q

Where is Earth’s magnetic field the strongest?

A

The field is strongest near Earth’s North and South Poles.

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21
Q

What is a Compass?

A

A compass is a magnet that sits on apivot. This magnet is often called the needle. Since opposite poles attract, the South Pole of the compass needle is attracted to Earth’s magnetic North Pole and vice versa

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22
Q

What is it called when you separate Protons and Electrons?

A

Electrostatic charge

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23
Q

What do charged objects attract?

A

Neutral objects

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24
Q

What is Static Electricity?

A

Build-up of an electric charge on the surface of any object moving once from one object to another.

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25
Q

Who discovered Static Electricity?

A

Accidentally discovered by Pieter van Musschenbroek and independently by Ewald Georg von Kleist

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26
Q

What is Potential Energy?

A

When charges separate, they have the potential to reconnect This means they have potential energy.

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27
Q

What is another name for Potential Energy?

A

Electric Energy

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28
Q

How does Lightning form?

A

Charges are separated in the atmosphere. When they have built up enough, they are attracted to the ground (neutral). The charges move to the ground, as Static Electricity. They have lots of potential energy due to the number of charges and the distance so lightning can be very dangerous.

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29
Q

What is a Conductor?

A

A material through which charged particles are able to move.

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30
Q

What is an example of a Conductor?

A

Copper or Steel

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31
Q

What is an Insulator?

A

A material that does not allow the movement of charged particles.

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32
Q

What is an example of an Insulator?

A

Plastic or Rubber

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33
Q

What is Electricity?

A

Moving charges

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34
Q

What do Conductors and Insulators do to Electricity?

A

Conductors allow the flow of electricity. Insulators resist the flow of electricity.

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35
Q

What is an Electrical Current?

A

The movement of electrons (negative) around a circuit. This flow is continuous not singular as in static electricity

36
Q

What is a Circuit?

A

The pathway travelled by electrical energy

37
Q

What does a Circuit do?

A

Carry energy from the battery to the light globe (for example) - Must be complete for them to work

38
Q

What must a Circuit have?

A

Must have:
- Energy Source: Provides continuous charges (Battery)

  • Pathway: Charges flow along this must be conductive (Wires)
  • Load: converts electrical energy into other forms (Light Bulb)
39
Q

How do charges move in a Circuit?

A

From the Positive (+) terminal of the energy source to the Negative (-) terminal of the energy source.

40
Q

What can a Switch do to a Circuit?

A

A switch can be added to the circuit to break the circuit when you want

41
Q

How do you measure the number of charges per second travelling around an electric circuit (Current)?

A

Amps (A) or milliamps (mA)

42
Q

How do you measure an electric current?

A

An Ammeter is used to measure the current.

43
Q

What is Voltage?

A

Voltage is a measure of the amount of energy in an electric circuit

44
Q

What is the Unit for Voltage?

A

V

45
Q

How do you measure Voltage?

A

A Voltmeter is used to measure the current. It must be connected parallel to the circuit

46
Q

What is Direct Current (DC)?

A

Electrons flow in one direction only. Is only found in battery powered objects

47
Q

What is Alternating Current (AC)?

A

Current changes direction 50 times every second. Is found in our homes and uses magnets to move the electrons

48
Q

What is Current?

A

A measure of the number of charges per second travelling around an electric circuit. Measured in Amps (A) and Milliamps (mA)

49
Q

What is Voltage?

A

A measure of the amount of energy in an electric circuit. Measured in Volts (V)

50
Q

What is Resistance?

A

The electrical resistance of a material is a measure of how difficult it is for charged electrons to move through it

51
Q

What is Resistance measured in?

A

Resistance is measured in units called ohms (Ω).

52
Q

What are Resistors?

A

Resistors are devices placed deliberately in circuits to create a precise quantity of resistance. They control the current by reducing the size of the current

53
Q

What does the 1st band of colour on resistors mean?

A

1st Digit

54
Q

What does the 2nd band of colour on resistors mean?

A

2nd Digit

55
Q

What does the 3rd band of colour on resistors mean?

A

Multiply by

56
Q

What does the 4th band of colour on resistors mean?

A

Tolerance

57
Q

What did George Ohm discover?

A

The relationship between voltage, current and resistance. As the VOLTAGE goes up, the current INCREASES. As the RESISTANCE goes up, the current DECREASES

58
Q

How do you calculate Voltage?

A

Current x Resistance

59
Q

How do you calculate Current?

A

Voltage ÷ Resistance

60
Q

How do you calculate Resistance?

A

Voltage ÷ Current

61
Q

How can we draw the flow of Electrical Energy?

A

Circuit Diagram

62
Q

What is the symbol for Light Globe?

A

——-(ˆ)——-

63
Q

What is the symbol for Switch?

A

——-/———

64
Q

What is the symbol for Connecting Wire?

A
65
Q

What is the symbol for Voltmeter?

A

——(V)———

66
Q

What is the symbol for Electric Motor?

A

——–(M)——–

67
Q

What is the symbol for Battery?

A

———⎮ |———

68
Q

What is the symbol for Ammeter?

A

———-(A)———–

69
Q

What is the symbol for Resistor?

A

———–⊏⊐————

70
Q

What is the symbol for Electric Bell?

A

________∩________

71
Q

What are the two possible types of connections?

A

Series Circuit or Parallel Circuit

72
Q

What is a Series Circuit?

A

The globes are connected side by side. Current goes through the first globe and then the second

73
Q

What is a Parallel Circuit?

A

The circuit has two or more branches and the globes are connected parallel.

74
Q

What does the Current and Voltage do in a Series Circuit?

A

CURRENT: always the same at all points of the circuit
VOLTAGE: split between globes

75
Q

What does the Current and Voltage do in a Parallel Circuit?

A

CURRENT: Split across branches
VOLTAGE: Always the same

76
Q

What to batteries do in a Series Circuit?

A

Electrons are given larger amounts of energy. When a battery is connected in a series, as an electron passes through the first battery it picks up a certain amount of energy and then additional energy as it passes through the second battery
EG: 2 x 1.5V batteries in a series circuit, each electron will pick up 3.0 Units of energy

77
Q

What to batteries do in a Parallel Circuit?

A

Each electron collects the same amount of energy. Each electron passes through either one battery or the other
Advantage: batteries last longer

78
Q

What is a Short Circuit?

A

Electric charges take the path of least resistance. Occurs when current flows along a different path from the one intended. Large currents can flow in a short circuit, causing batteries to go flat quickly. Short circuits can lead to wires heating up, causing damage or even fire.

79
Q

What is a Fuse?

A

A fuse is a switch or thin piece of wire that burns up quickly when current starts flowing too fast within a circuit. A sudden increase in current will cause the fuses to break the circuit. This stops the current from flowing and may prevent electrocution

80
Q

What are Diodes?

A

Diodes are semi conductive. They allow current to flow in one direction only (forward-biased) - Positive to Negative. If the diode is connected in reverse current will not flow (reverse-biased). The diode’s symbol is an arrow and it points in the direction of conventional flow
(Opposite direction to electron flow)

81
Q

What is an LED?

A

LED stands for Light-Emitting Diode. LED is a type of diode that:
- Restricts current flow to one direction only, also
- Emits light of a particular colour
Examples of LED:
- Remote controls for TV
- Light bulbs

82
Q

What is a Solenoid?

A

An electromagnet consisting of a coil wire wrapped around a bar magnet.

83
Q

What does a single current wire create?

A

Circular magnetic field

84
Q

What happens in to a Parallel circuit if you add more globes?

A

Makes the overall resistance lower and the current higher

85
Q

Explain how a van de graaff generator creates static electricity?

A
  • The rubber belt moves over the rollers.
  • Electrons move to the inside of the belt, leaving the outside with a positive charge
  • The positive charge accumulates on the metal sphere

Science Sem 2 Exams (3 decks)

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