Static Electricity

Question 1

protons are positive/negative/neutral

Answer 1

positive

Question 2

neutrons are positive/negative/neutral

Answer 2

neutral

Question 3

where are protons and neutrons found in an atom

Answer 3

in the nucleus

Question 4

electrons are positive/negative/neutral

Answer 4

negative

Question 5

where are electrons found in an atom

Answer 5

orbiting the atom

Question 6

can you remove protons from the nucleus?

Answer 6

it is almost impossible

Question 7

can you remove electrons from round the outside?

Answer 7

it it very easy

Question 8

how do you charge a polythene rod?

Answer 8

when a polythene rod is rubbed, the friction causes the electrons in the duster to transfer to the polythene rod

the polythene then has more electrons than protons and is negatively charged

the duster then has fewer electrons than protons and is positively charged

Question 9

how do you charge an acetate rod?

Answer 9

when the acetate rod is rubbed, the friction causes the electrons in the acetate rod to transfer to the duster

the acetate now rod has more protons than electrons and is positively charges

the duster now has more electrons than protons and is negatively charged

Question 10

two negatively charged rods are held up to each other

what do they do and why

Answer 10

they move away from each other

like charges repel

Question 11

two postively charged rods are help up to each other

what do they do and why

Answer 11

they move away from each other

like charges repel

Question 12

two postively charged rods are help up very close to each other

what do they do and why

Answer 12

they move away from each other with a larger force as they are close together

like charges repel

Question 13

two negatively charged rods are help up far away from each other

what do they do and why

Answer 13

they move away from each other wuth a smaller force as they are further apart

like charges repel

Question 14

one postively charged rod and one negatively charged rod are help up to each other

what do they do and why

Answer 14

they come closer together

opposite charges attract

Question 15

what does GLE stand for

Answer 15

Gold Leaf Electroscope

Question 16

what does a GLE do?

Answer 16

this device detects electrical charge (positive or negative)

the gold leaf sticks up when charges are near the plate at the bottom

the greater the charge, the greater the angle of the leaf

Question 17

what happens when a polythene rod is held up to a GLE

Answer 17

electrons in the GLE are repelled by the electrons in the rod

like charges repel so the leaf rises

Question 18

what happens when an acetate rod is held up to a GLE

Answer 18

electrons in the GLE are attracted to the acetate rod and move upwards

positive charges attract so the leaf rises

Question 19

how do you charge the GLE by induction

Answer 19

bring a postively charged rod close the the GLE

toughing the GLE with a finger allows electrons from the Earth to make the system neutral again, so the leaf goes down

remove the finger then remove the rod. this means we have an excess of negative charges which makes the leaf rise

Question 20

how does a photocopier work?

Answer 20

the copying plate is given a charge

an image of the page to be copied is projected onto the charged copying plate

where light hits the page the charge leaks away, leaving a pattern on the page

black ink powder is attracted to the charges parts of the plate

black ink powder is transferred onto a piece of paper

the paper is heates so the powder melts and sticks to the page

this is now a photocopy of the original plate

Question 21

what is electrostatic precipitator?

Answer 21

device used in chimneys to remove smoke from waste gases before they leave chimneys

Question 22

why does the smoke need to be removed by an electrostatic precipitator in chimneys?

Answer 22

smoke particles, such as unreacted carbon, damage buildings and make it difficult to breath

Question 23

how does an electrostatic precipitator work?

Answer 23

smoke particles gain a negative charge as they pass a negatively charged grid

they then become attracted to the positively charged collecting plates on the side of the chimney

once the plates are knocked, the smoke particles fall into a collector and the clean air passes out through the chimney

Question 24

what is the use of the grid in an electrostatic precipitator?

Answer 24

the metal grid is given a high votlage

the grid that the smoke passes through may be positively or negatively charged

if the grid is negatively charged then the smoke particles gain electrons, if it is positively charged then they particles lose electrons

depending on their charge, the dust particles are attracted to the oppositely charged collceting plates

opposite charges attract

Question 25

label this diagram of a Van de Graaf generator

Answer 25

Question 26

how do you discharge negatively charged Van de Graaff Generator

Answer 26

the electrons conduct through the person to the ground

this leaves the dome neutrally charged

Question 27

how do you discharge a positively charged Van de Graaff Generator?

Answer 27

electrons conduct from the ground through the person to the dome

this leaves it neutrally charged

Question 28

why does someone’s hair to raise when they hold onto a Van de Graaff Generator?

Answer 28

electrons repel each other and move through your boyd (including your hair)

each strand of hair is negatively charges

they repel each other and the force makes them stand on end

Question 29

how does a charged balloon stick to the ceiling?

Answer 29

the negatively charged balloon is brought up to the neutrally charges celing

the electrons in the celing repel away from the balloon

this means the electron in the balloon and the protons in the ceiling can attract

this means the balloon can stick to the ceiling

Question 30

why does a charged balloon that had been stuck to a ceiling fall after a while?

Answer 30

the elctrons in the balloon escape into the air

this means the balloon becomes neutrally charged

the electrons in the ceiling then move back down

this makes the balloon drop from the ceiling

there is no longer any force between the balloon and the ceiling

Question 31

how does a negtaively charged rod collect neurally charged peices if paper?

Answer 31

the negatively charged rid induces a positive charge at the top of the first piece of paper which causes them to attract

the electrons are repelled to the bottom of each piece of paper by the electrons in the negatively charged rod rod

Question 32

how does a lightning conductor work to protect buildings?

Answer 32

copper metal is fixed to the outside of the building

it reaches to the top of the building (extensive tops have several, can be one or many depending on size and shape of building)

other end is fixed into ground

this provides a very low resistance pathway for lightning to reach the ground

Question 33

what would happen if buildings weren’t protected by a lightning conductor?

Answer 33

lightninig must pass through brick or stone

can shatter building

yurns water to steam rapidly causing huge cracks to form

can leave buildings unstructurally sound

can get into electric circuits

Question 34

what are the dangers of refuelling an aircraft?

Answer 34

the fuel has to pass through a hose to enter the aircraft

this causes friction to be created and a charge to go up the plane, tanker and hose

because there is lots of electrical wirign and circuits in an aircraft, this charge may result in a spark

fuel is very flammable so the spark can ignite and result in a hige fire spreading quickly through the aircraft

Question 35

how do you prevent fire and sparks when refuelling an aircraft?

Answer 35

aircrafts and tankers should be earthed (discharged) before they are refuelled

if it is discharged then it won’t result in a spark

a metal wire in used to earth the objects as the charge seeks the easiest route to the ground through the wire

this makes the charge neutral

Question 36

when spray painting, why is the gun positively charged? (assuming the car is negaitively charged)

Answer 36

each droplet of paint has electrons pulled from it by the positively charged gun

this makes them repel each other, resulting in an even spray paint (no clumps)

Question 37

when spray painting, why is the car door negatively charged (assuming the gun is positively charged)?

Answer 37

the positively charged paint droplets are attracted to the cra door which is negatively charged

Question 38

what are the advantages of spray painting with charged guns and car doors?

Answer 38

less paint is wasted

front and back can be painted simultaneously so it can save time and can get into hard to reach areas

better quality paint job

Question 39

a man becomes positively charged by walking across nylon carpet

when he touches an earthed light switch, he feels a shock as he loses excess charge

explain how he loses excess charge

Answer 39

electrons from the ground (Earth) are attracted to the protons in the man because opposite charges attract

Question 40

when jane takes off her woolen jumper she hears a crackling sound and sees flashes of light

It is thought that the …….. between her jumper and blouse is producing …… charges

the jumper become positively charged because ……. are being removed from it

because the jumper and blouse have opposite charges they ….. each other and this makes it difficult for the jumper to be removed

Answer 40

when jane takes off her woolen jumper she hears a crackling sound and sees flashes of light

It is thought that the friction between her jumper and blouse is producing electrostatic charges

the jumper become positively charged because **electrons **are being removed from it

because the jumper and blouse have opposite charges they attracteach other and this makes it difficult for the jumper to be removed

Question 41

a golfer stands under a device made up of aluminium poles in a triangular shape (No base) with two spikes in the ground

explain how the aluminumpoles stop lightning from striking the golfer

Answer 41

aluminium is metal

the small spike at the top attracts the lightning and it runs to the earth to be discharges via the aluminium

the aluminium provides a low path of resistant

the lightning cannot reach the person

Question 42

What happens with insulators and static electricity?

Answer 42

insulators do not allow electric charges to move through them

some insulators can become electrically charged when they’re rubbed with a different insulator

Question 43

what is the relationship between the static charge stored and the potential difference between it and the earth

Answer 43

the greater the static charge stored, the greater the potential difference between it and the earth

Question 44

What happens if the if the p.d. becomes high enough?

Answer 44

the greater the charge on an isolated object, the greater the voltage between it and the Earth

if the voltage becomes gets big enough a spark may jump across a gap

Question 45

why can’t metals store a static charge unless they are isolated? but insulators can?

Answer 45

metals are good conductors (poor insulators)

if one end of a piece of metal is made positive, the electrons will be attracted towards it and because they are free, they can move towards it

static charge only builds up in insulators (these are materials that will not allow the flow of charged particles (nearly always electrons) through them)

static charge won’t build up on conductors unless they are isolated because as soon as you put too many electrons in one place, they repel each other and spread out, reducing or eliminating the effect

on insulators, the charge can’t spread out - so you get a noticeable effect

You can give metal objects static charge as long as the whole object is insulated from the rest of the world so that charge cannot escape from it (even though the charge is spread evenly throughout the whole metal object)

if you give a metal a charge you need to isolate it from the earth otherwise the charge would conduct down to earth - isolating metals prevents this

Question 46

how does lightning work?

Answer 46

lots of small bits of ice bump into each other as they move around - all these collisions cause a build up of electrical charge

the whole cloud fills up with electrical charges

lighter, positively charged particles form at the top of the cloud

heavier, negatively charged particles sink to the bottom of the cloud

when the positive and negative charges grow large enough, a giant spark (lightning) occurs between the two charges within the cloud

opposite charges attract so a positive charge builds up on the ground beneath the cloud

the ground’s electrical charge concentrates around anything that sticks up (mountains, people, or single trees)

the charge coming up from these points eventually connects with a charge reaching down from the clouds and lightning strikes

in short: Rain drops and ice bump together inside storm clouds, knocking off electrons and leaving the top of the cloud positively charged and the bottom of the cloud negatively charged. This created a huge voltage and a big spark

Question 47

Explain how a student uses different plastic rods, a cloth and a hanger attached to a retort stand to demonstrate the law of electrostatics

Answer 47

charge one rod (plastic) by rubbing it with a cloth - supsend this rod on the hanger

charge another rod (similar plastic to other rod) by rubbing it with a cloth - hold this rod near the suspended rod

the rods will repel as like charges repel

charge a different type of rod by running it with the cloth

the rods will attract as opposite charges attract

Question 48

What is the law of electrostatics?

Answer 48

like charges repel

oppisite charges attract

Question 49

How does an inkjet printer work?

Answer 49

1. Tiny droplets of ink are forced out of a fine nozzle, making them electrically charged
2. The droplets are deflected as they pass between two metal plates. A voltage is applied to the plates - one is negative and the other is positive
3. The droplets are attracted to the plate of the opposite charge and repelled from the plate with the same charge
4. The size and direction of the voltage across each plate changes so each droplet is deflected to hit a different place on the paper
5. Loads of tiny dots make up your printout

Question 50

Why do clothes cackle?

Answer 50

When synthetic clothes are dragged over each other (like in a tumlr dryer or over your head) electrons get scrapped off, leaving static charges on both parts - they attract

little sparks/shocks occur as the charges rearrange themselves