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GCSE Physics > Electrostatics and Magnetism > Flashcards

Electrostatics and Magnetism Flashcards

1
Q

what is the unit used to measure charge?

A

coulombs (c)

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2
Q

which charges attract and repel?

A

opposite charges attract and like charges repel

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3
Q

what are atoms composed of?

A
  • protons
  • neutrons
  • electrons
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4
Q

what are the charges of protons, electrons and neutrons?

A
  • protons: +1
  • electrons: -1
  • neutrons: 0
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5
Q

what does charging a body do?

A

involves the addition or removal of electrons- charging atoms creates ions

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6
Q

what do conductors do when touching electrons compared to insulators?

A

conductors such as metals allow electrons to flow through them, whereas insulators like plastics impede the flow of electrons.

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7
Q

what happens when two insulators are rubbed together?

A

friction causes electrons to move from one to the other and they become charged. the material that loses electrons becomes positively charged and the material that gains electrons becomes negatively charged.

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8
Q

can protons be transferred?

A

no, they are fixed in the nucleus.

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9
Q

draw the structure of an atom.

A

electrostatics : picture 1

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10
Q

why does a charged balloon stick to a wall?

A

electrostatics: picture 2

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11
Q

what does the nucleus of an atom contain?

A

protons and neutrons.

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12
Q

when does an atom have equal numbers of protons and neutrons?

A

when the atom is uncharged.

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13
Q

what is a charged atom called?

A

an ion.

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14
Q

name 4 examples of the uses of electrostatics.

A
  • electrostatic paint spraying
  • electrostatic smoke precipitator
  • electrostatic crop spraying
  • a photocopier
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15
Q

explain electrostatic paint spraying.

A
  • the spray nozzle is connected to the negative terminal
  • this makes all the paint droplets negatively charged.
  • the paint droplets are sprayed from the spray nozzle and repel each other making them spread out.
  • the metal being sprayed is connected to the positive or to an earth terminal, so the droplets are attracted to it.
  • advantages to this are even coating and less mess.
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16
Q

explain the electrostatic smoke precipitator.

A

electrostatics: picture 3
- the smoke particles pass through the grid and pick up a negative charge.
- as the charged smoke particles move up trough the chimney, they are oppositely attracted to the charged plates and the grid is negatively charged.
- when the oppositely charges plates are covered with particles, they are tapped so that the particles fall to the bottom and can be cleared away.

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17
Q

explain electrostatic crop spraying.

A

electrostatics: picture 4
- if the insectide is given an electrostatic charge as it leaves the aircraft, then much more of the spray reaches its target and the spray droplets are spread out more evenly.
- the insectide droplets spread out more evenly because they all have the same charge and repel each other.

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18
Q

explain how the photocopier works.

A
  • a rotating drum is given a positive charge.
  • a light shines onto the paper to be copied, and the reflection falls on the drum.
  • the drum is made of a special material that conducts when light falls on it, so the positive charge leaks away where the light falls.
  • black powder that is negatively charged is sprayed across the drum (toner).
  • the toner is attracted only to the charge area.
  • a sheet of paper is passed over the drum.
  • the toner is attracted only to the charge area.
  • a sheet of paper is passed over the drum
  • the toner is transferred to the paper, and is heated to fuse it to the paper.
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19
Q

give an example of charging by induction.

A

electrostatics: picture 5

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20
Q

what happens when a rod is rubbed with a cloth?

A

electrons are transferred from the rod onto the cloth and the rod becomes positively charged. the charges cannot move within the insulator so they build up- know as static electricity.

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21
Q

what are the dangers of static electricity?

A

lightning. electrostatic charge can build up on clouds due to friction. when the charge becomes large enough, the clouds discharge through the air to the earth. this results in lighting.

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22
Q

what is charging by induction?

A

a charging method which charges an object without actually touching the object to any other charged object. the charging by induction process is where the charging particle is held near an uncharged conductive material that is grounded on a neutrally charged material.

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23
Q

what do field lines look like around this magnet? is this a uniform magnetic field?

A

electrostatics: picture 6

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24
Q

what is the difference between a hard magnet and a soft magnet?

A

magnetically hard materials are substances that can be permanently magnetised (e.g. steel) and are hard to magnetise and demagnetise whereas magnetically soft materials are substances that can only be temporarily magnetised (e.g. iron) and are easily magnetised/ easily demagnetised.

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25
Q

explain the danger of refuelling vehicles.

A

fuel is an insulator and charge can be transferred as it flows through an insulating pipe. this happens because there is friction between the fuel and the pipe. when a nozzle is brought close to the fuel tank, a spark can jump between the two, igniting the fuel. this can cause a serious explosion. even if the car is discharge, charge can build up when fuel flows through the insulating pipe! the pipe nozzle is made to conduct by making it from conductive material or connecting an Earth strap to it. any charge can be safely conducted away.

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26
Q

name the 4 examples of the dangers of electrostatics.

A
  • lightning strike
  • aircraft/cars moving through the air
  • static and oxygen
  • refuelling vehicles
27
Q

explain lightning strike.

A

a buildup of positive charge accumulates on the ground beneath the cloud, attracted to the negative charge in the bottom of the cloud.
if the difference between the charges is great enough, lighting will strike the object or the the ground.
this is a giant spark.

28
Q

what is earthing?

A

earthing is creating a pathway for electrons to move from a charged object to the ground or the other way around.

29
Q

what is the charge of a proton?

A

positive

30
Q

what is the charge of a neutron?

A

zero charge

31
Q

what is the charge of an electron?

A

negative

32
Q

what does every atom contain?

A

a nucleus.

33
Q

describe the gold leaf electroscope.

A

electrostatics: picture 7
1) a charged balloon is brought close to the electroscope.
2) the gold leaf gains electrons as well as the rod.
3) as the gold leaf and rod are both negatively charged, they repel one another.
4) the gold leaf moves down.

34
Q

give a method of charging by induction and explain it.

A

electrostatics: picture 8
a charge is induced in an object by charge separation. a conductor is used to allow charge to leak away- repelled by the negative rod. the object is now positively charged.

35
Q

what does it mean when the field lines are closer together, compared to when they are further apart?

A

if the field lines are closer together, the stronger the magnetic field is, and the farther apart they are, the weaker the magnetic field is.

36
Q

what are the three ways you can make a magnet?

A

1) stroke a magnet along a paperclip from one end to the other and then, starting from the same place, repeat the movement. the more times this is done, the more magnetic the clip becomes.
2) hold a nail in a magnetic field and it it with a hammer.
3) hold a magnetic material in a strong magnetic field.

37
Q

what is the standard form for pico?

A

10^-12

38
Q

what is the standard form for nano?

A

10^-9

39
Q

what is the standard form for milli?

A

10^-3

40
Q

what is the standard form for micro?

A

10^-6

41
Q

what is the standard form for giga?

A

10^9

42
Q

what is the standard form for centi?

A

10^-2

43
Q

what is the standard form for deci?

A

10^-1

44
Q

what is the standard form for kilo?

A

10^3

45
Q

what is the standard form for mega?

A

10^6

46
Q

what is the standard form for tera?

A

10^12

47
Q

what is the method to find the shape of the magnetic field?

A

iron filings:
- cover the magnet in clingfilm
- draw around the magnet
- place the magnet under the paper
- sprinkle the iron filings onto the page
- tap the page
- observe the field lines

48
Q

what is the method to find the shape and direction of the magnetic field?

A
  • use compass
  • place around the magnet
  • line up the compass with N
  • mark a point
  • continue and join points
  • arrows always point from N -> S
49
Q

which materials are magnetic?

A

iron, cobalt and nickel.

50
Q

what do field lines look like around these magnets? are these uniform magnetic fields?

A

electrostatics: picture 9 and picture 10
1. no, this is not a uniform magnetic field.
2. yes, this is a uniform magnetic field.

51
Q

what happens when permanent magnets are repeatedly knocked?

A

the strength of their magnetic field is reduced.

52
Q

what is it called when you covert a magnet into a non-magnet?

A

demagnetisation.

53
Q

what actually happens when you make a magnet?

A
  • a magnetic material is made of domains
  • they are indicated by the arrows in the metal material
  • in unmagnetised objects, all of the magnetic domains are pointing in random directions
  • when the metal becomes magnetised, e.g. when it is rubbed with a strong magnet, all like magnetic poles line up and point in the same direction
  • the metal becomes a magnet
    electrostatics: picture 11
54
Q

explain the static oxygen danger.

A

it is dangerous when there are flammable gases or a high concentration of oxygen. a spark could ignite the gases and cause an explosion.

55
Q

explain the danger of aircraft/cars moving through the air.

A

when cars or aircraft move through the air, they pick up an electric charge i.e. electrons are lost from the car and it becomes positively charged. when the vehicle is refuelled, the difference in charge between it and the refuelling pipe can cause a spark or discharge. if the vehicle is first earthed, then any charge is lost (discharged). the vehicle is now neutral and no spark can occur- no explosion.

56
Q

what is an experiment to investigate charge by friction?

A
  1. Take a polythene rod, hold it at its centre and rub both ends with a cloth
  2. Suspend the rod, without touching the ends, from a stand using a cradle and nylon thread
  3. Take an acetate rod and rub it with another cloth.
  4. Without touching the ends of the acetate rod bring each end of the acetate rod up to, but without touching, each end of the polythene rod
  5. Record any observations
  6. Repeat for different materials
57
Q

describe an experiment to demonstrate the two types of charge using different insulating cloths.

A
  • charge a polythene rod by friction
  • place it carefully on the top of an upside down watch glass
  • charge a second polythene or acetate rod and hold it next to but not touching the balanced polythene rod.
  • move it closer to the rod and further from the rod.
    OR
  • gold leaf electroscope
    1) a charged balloon is brought close to the electroscope.
    2) the gold leaf gains electrons as well as the rod.
    3) as the gold leaf and rod are both negatively charged, they repel one another.
    4) the gold leaf moves down.
58
Q

describe an experiment to charge a metal rod.

A
  1. Hold a metal rod
  2. Rub the metal with a duster
  3. Hold the end of the rod near small pieces of paper
59
Q

what is the explanation of the results of charging a plastic rod with a cloth.

A

The plastic rod is charged by friction. Electrons transfer from the cloth to the rod OR the rod to the cloth depending on the type of plastic. The paper is attracted to the charged rod because a charge is induced in the paper which attracts it to the rod.

60
Q

what is the explanation of the results of charging a metal rod?

A

The metal rod is a conductor. Any charge that is transferred to the rod will conduct through the metal to your hand. Your hand acts as an Earth wire and no charge builds up on the rod. The metal rod remains neutral. The paper is not attracted to the rod- it is not charge.

61
Q

explain the results of an experiment to demonstrate the two types of charge using different insulating cloths.

A

Polythene rods is charged negatively by friction. Like charges repel. The closer the rods are the greater the electrostatic force of repulsion Polythene rod is charged negatively by friction. Acetate is charged positively by friction. Unlike charges attract.

62
Q

describe the experiment of a balloon rubbing on a sweater.

A
  1. Rub a balloon on a head or polyester sweater
  2. Hold balloon near wall or ceiling
63
Q

explain the results of an experiment of a balloon rubbing on a sweater.

A

The balloon charges negatively. Electrons transfer from the sweater to the balloon. When the balloon is held near the wall, electrons in the wall are repelled away from the surface. This induces a charge in the wall and the surface becomes positively charged. Like charges attract. The negative balloon is attracted to the positively charged surface of the wall.

GCSE Physics (5 decks)

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