Electrostatics

Question 1

what is a conductor

Answer 1

a material that allows charge to flow through it easily

Question 2

what are some examples of a conductor

Answer 2

silver, copper, aluminium, steel, gold

Question 3

what do conductors tend to be

Answer 3

metals

Question 4

what are conductors made up of

Answer 4

positively charged metal ions with their outermost electrons delocalised. this means the electrons are free to move

Question 5

why do metals conduct electricity very well

Answer 5

current is the rate of flow of electrons so the more easily electrons are able to flow, the better the conductor

Question 6

what is an insulator

Answer 6

a material that has no free charges, hence does not allow the flow of charge through them very easily

Question 7

what are some examples of insulators

Answer 7

rubber, plastic, glass, wood

Question 8

although insulators are not very good at conducting, what else can they do

Answer 8

they conduct a little electricity in the form of static electricity. for example, two insulators can build up charge on their surfaces and if they touch this would allow that charge to be conducted away

Question 9

what is the aim of the experiment for investigating charging by friction

Answer 9

to investigate how insulating materials can be charged by friction

Question 10

what are the variables in investigating charging by friction

Answer 10

independent - rods of different material
dependent - charge on the rod
controls - time spent rubbing the rod, using the same type of cloth, using the same length of rod

Question 11

what equipment is needed in investigating charging by friction

Answer 11

polythene rod, rods of different materials (perspex, acrylic, ebonite, glass, wood), cloths (one for each material), cradle, nylon string, and a wooden stand

Question 12

what is the purpose of the polythene rod in investigating charging by friction

Answer 12

to charge and hang in a cradle to test against each material

Question 13

what is the purpose of the rods made of different materials in investigating charging by friction

Answer 13

to charge and hold against the polythene rod to observe effects

Question 14

what is the purpose of the cloths in investigating charging by friction

Answer 14

used to rub the materials to charge them

Question 15

what is the purpose of the cradle in investigating charging by friction

Answer 15

used to support the rods to keep them horizontal

Question 16

what is the purpose of the nylon string in investigating charging by friction

Answer 16

to hang the rods

Question 17

what is the purpose of the wooden stand in investigating charging by friction

Answer 17

to attach the string and cradle to

Question 18

what is the method in investigating charging by friction

Answer 18

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 a perspex rod and rub it with another cloth
4) without touching the ends of the perspex rod bring each end of the perspex rod up to, but without touching, each end of the polythene rod
5) record any observations
6) repeat for different materials

Question 19

what happens when two insulating materials are rubbed together

Answer 19

electrons will pass from one insulator onto the other insulator

Question 20

what charge is given to a polythene rod when rubbed by the cloth and why

Answer 20

a negative charge, and this happens because electrons move from the cloth to the rod. electrons are negatively charged hence the polythene rod becomes negatively charged

Question 21

where do the electrons move when a polythene rod is rubbed by a cloth

Answer 21

to the rod

Question 22

where do the electrons move when a acetate rod is rubbed by a cloth

Answer 22

to the cloth

Question 23

what charge does the material have if the material is repelled from the polythene rod

Answer 23

the materials have the same charge

Question 24

what charge does the material have if the material is attracted to the polythene rod

Answer 24

the materials have opposite charges

Question 25

how could you improve the outcome of the experiment

Answer 25

consider investigating a variable with a numerical result. for example, the independent variable could stay the same (using rods of different material). the dependent variable could change to be the number of paper circles picked up by each rod

Question 26

what is the advantage of having a numerical data outcome of an experiment

Answer 26

more analysis can be carried out e.g. creating a graph or a chart. better conclusions can be drawn e.g. the rod made of ___ picked up more circles of paper than the other rods, therefore it became the most charged

Question 27

what happens when certain insulating materials are rubbed against each other

Answer 27

they become electrically charged

Question 28

what happens to the charge on the insulators, and give an example

Answer 28

it remains and cannot immediately flow away. one becomes positive and one becomes negative. an example of this is a plastic or polythene rod being charged by rubbing it with a cloth. both the rod and cloth are insulating materials

Question 29

what are the different charges that a particle could be

Answer 29

positive, negative or neutral

Question 30

give an example of a negative, neutral and positive particle

Answer 30

electron, neutron and proton

Question 31

when an object gains electrons, what charge does it now possess

Answer 31

negative charge

Question 32

when an object loses electrons, what charge does it now possess

Answer 32

positive

Question 33

what happens when two charged particles are close together

Answer 33

they exert a force on each other

Question 34

what are the two possible forces that could come from moving two charged particles close together

Answer 34

attractive (the objects get closer together), or repulsive (the objects move further apart)

Question 35

what decides whether two objects attract or repel

Answer 35

their charge

Question 36

what force will be exerted on two objects with opposite charges

Answer 36

they will attract

Question 37

what force will be exerted on two objects with same charges

Answer 37

they will repel

Question 38

what charge to objects have initially

Answer 38

they are electrically neutral, meaning the negative (electrons) and positive charges are evenly distributed

Question 39

what happens when electrons are transferred through friction

Answer 39

one object becomes negatively charged and one object becomes positively charged. the object to which the electrons are transferred to becomes negatively charged. the object from which the electrons leave from becomes positively charged

Question 40

what does the difference in charges lead to

Answer 40

a force of attraction between two objects

Question 41

what are two uses of static electricity

Answer 41

photocopiers, and insecticide

Question 42

how do photocopiers use static electricity

Answer 42

to copy documents, mostly in black and white

Question 43

explain how a photocopier uses static electricity to copy paper documents

Answer 43

an image of the document is projected onto a positively charged copying plate. the plate loses its charge in the light areas and keeps the positive charge in the dark areas (i.e the text). a negatively charged black toner powder is applied to the plate and sticks to the part where there is a positive charge. the toner is then transferred onto a new blank sheet of white paper. the paper is heated to make sure the powder sticks (hence why photocopied paper feels warm). the photocopy of the document is now made

Question 44

how do inkjet printers work in a similar way to photocopiers

Answer 44

instead of the black toner powder, a small jet of coloured ink is negatively charged and attracted to the correct place on the page

Question 45

how must insecticide sprayers spray crops effectively whilst using a minimal amount of chemicals

Answer 45

the sprayer has to deliver the chemicals as a fine mist and cover a large area

Question 46

how does an insecticide sprayer deliver the chemicals as a fine mist and cover a large area

Answer 46

the insecticide is given an electrostatic charge (e.g. positive) as it leaves the sprayer. the droplets of insecticide then repel each other since they are the same charge. this ensures that the spray remains fine and covers a large area

Question 47

what is the advantage of the insecticide being attracted to the negative charges on earth

Answer 47

they will fall quickly and are less likely to be blown away

Question 48

what are some situations where static electricity can pose a hazard

Answer 48

the risk of electrocution (e.g from lightning). the risk of a fire or explosion due to a spark close to a flammable gas or liquid

Question 49

what is used to prevent the build-up of charge

Answer 49

earthing, and is done by connecting vehicles to the earth with a conductor

Question 50

how is the build-up of static charge a potential danger when refuelling aeroplanes

Answer 50

fuel runs through pipes at a fast rate. this fuel is very flammable. the friction between the fuel (a liquid insulator) and the pipe causes the fuel to gain charge. if this charge were to cause a spark, the fuel could ignite and cause an explosion

Question 51

how is the build-up of static charge when refuelling aeroplanes prevented

Answer 51

the fuel tank being connected to the earth with a copper wire called the bonding line during the refuelling. the conductor earths the plane by carrying the charge through to the earth which removes the risk of any sparks