Static Electricity Flashcards
protons are positive/negative/neutral
positive
neutrons are positive/negative/neutral
neutral
where are protons and neutrons found in an atom
in the nucleus
electrons are positive/negative/neutral
negative
where are electrons found in an atom
orbiting the atom
can you remove protons from the nucleus?
it is almost impossible
can you remove electrons from round the outside?
it it very easy
how do you charge a polythene rod?
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
how do you charge an acetate rod?
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
two negatively charged rods are held up to each other
what do they do and why
they move away from each other
like charges repel
two postively charged rods are help up to each other
what do they do and why
they move away from each other
like charges repel
two postively charged rods are help up very close to each other
what do they do and why
they move away from each other with a larger force as they are close together
like charges repel
two negatively charged rods are help up far away from each other
what do they do and why
they move away from each other wuth a smaller force as they are further apart
like charges repel
one postively charged rod and one negatively charged rod are help up to each other
what do they do and why
they come closer together
opposite charges attract
what does GLE stand for
Gold Leaf Electroscope
what does a GLE do?
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
what happens when a polythene rod is held up to a GLE
electrons in the GLE are repelled by the electrons in the rod
like charges repel so the leaf rises
what happens when an acetate rod is held up to a GLE
electrons in the GLE are attracted to the acetate rod and move upwards
positive charges attract so the leaf rises
how do you charge the GLE by induction
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
how does a photocopier work?
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
what is electrostatic precipitator?
device used in chimneys to remove smoke from waste gases before they leave chimneys
why does the smoke need to be removed by an electrostatic precipitator in chimneys?
smoke particles, such as unreacted carbon, damage buildings and make it difficult to breath
how does an electrostatic precipitator work?
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
what is the use of the grid in an electrostatic precipitator?
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
label this diagram of a Van de Graaf generator
how do you discharge negatively charged Van de Graaff Generator
the electrons conduct through the person to the ground
this leaves the dome neutrally charged
how do you discharge a positively charged Van de Graaff Generator?
electrons conduct from the ground through the person to the dome
this leaves it neutrally charged
why does someone’s hair to raise when they hold onto a Van de Graaff Generator?
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
how does a charged balloon stick to the ceiling?
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
why does a charged balloon that had been stuck to a ceiling fall after a while?
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
how does a negtaively charged rod collect neurally charged peices if paper?
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
how does a lightning conductor work to protect buildings?
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
what would happen if buildings weren’t protected by a lightning conductor?
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
what are the dangers of refuelling an aircraft?
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
how do you prevent fire and sparks when refuelling an aircraft?
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
when spray painting, why is the gun positively charged? (assuming the car is negaitively charged)
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)
when spray painting, why is the car door negatively charged (assuming the gun is positively charged)?
the positively charged paint droplets are attracted to the cra door which is negatively charged
what are the advantages of spray painting with charged guns and car doors?
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
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
electrons from the ground (Earth) are attracted to the protons in the man because opposite charges attract
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
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
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
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
What happens with insulators and static electricity?
insulators do not allow electric charges to move through them
some insulators can become electrically charged when they’re rubbed with a different insulator
what is the relationship between the static charge stored and the potential difference between it and the earth
the greater the static charge stored, the greater the potential difference between it and the earth
What happens if the if the p.d. becomes high enough?
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
why can’t metals store a static charge unless they are isolated? but insulators can?
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
how does lightning work?
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
Explain how a student uses different plastic rods, a cloth and a hanger attached to a retort stand to demonstrate the law of electrostatics
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
What is the law of electrostatics?
like charges repel
oppisite charges attract
How does an inkjet printer work?
- Tiny droplets of ink are forced out of a fine nozzle, making them electrically charged
- 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
- The droplets are attracted to the plate of the opposite charge and repelled from the plate with the same charge
- The size and direction of the voltage across each plate changes so each droplet is deflected to hit a different place on the paper
- Loads of tiny dots make up your printout
Why do clothes cackle?
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
