P4a

Question 1

What is a build up of static caused by?

Answer 1

-by friction
1-electrons have a negative charge
2-two insulating layers rub together
3-electrons scrape off one and onto the other
4-leaving a positive static charge on the one that lost electrons and a negative charge on the one that gained electrons
-the way electrons are transferred depends on the two materials involved, e.g.polythene(gains electrons) and acetate(loses electrons) rod being rubbed with a cloth duster

Question 2

How does static electricity attract dust?

Answer 2

• dust particles are charged and will be attracted to anything with opposite charge
• many things in the house are insulators so get easily charged and attract the dust particles

Question 3

How does static electricity make clothing cling and crackle?

Answer 3

• dragging synthetic clothes over each other (dryer) or over you head, electrons are scraped off, leaving static charges on both parts
• and therefore leading to attraction, clinging clothes to you and sparks and shocks as the charges rearrange themselves

Question 4

How does static electricity give you shocks from door handles?

Answer 4

• walking on a nylon carpet wearing shoes with insulating soles causes a charge to build in your body
• if you touch metal door handle charge flows through the conductor and you get a shock

Question 5

How can static electricity building up in clothes be dangerous?

Answer 5

• lots of a static charge can build up on clothes made of synthetic materials, if they rub against other synthetic materials
• charge can become large enough to make a spark

Question 6

How can filling planes with fuel be dangerous?

Answer 6

• when an aircraft takes on fuel, fuel rubs against the rubber tubes in the plane causing a charge
• if a spark is caused the plane will explode
• so a wire is connected to the plane and fuel take before hand
• this earths both of them and stops a spark from forming

Question 7

Why are things insulated?

Answer 7

-insulating mats and shoes with insulating soles stop static electricity from moving through them and so they stop you from getting a shock

Question 8

How do anti-static cloths work?

Answer 8

-conductive so they carry charge away from objects they’re used to wipe

Question 9

How do anti-static sprays and liquids work?

Answer 9

• make the surface of a charged object conductive

- providing an easy path for charges to move away and not cause problems

Question 10

How can dangerous sparks be prevented?

Answer 10

• by connecting a charged object to the ground using a conductor
• this is called earthing and provides and easy route for static charge to travel into the ground
• meaning no charge can build up and cause a shock or spark

Question 11

How is static electricity used in spray paints?

Answer 11

-electrostatic paint sprayers used on bikes and cars
1-spray gun is charged, which charges up the small drops of paints
2-each drop of paint repels the others because they have the same charge (spray is very fine)
3-object being painted is given the opposite charge to the gun,
4-this attracts the fine spray of paint
5-this method gives and even coat and hardly any paint is wasted
6-parts of car or bicycle facing away from spray gun still receive paint (there are no shadows)

Question 12

How is static electricity used in dust preciptators?

Answer 12

1-smoke particles reach bottom of chimney and meet a wire grid or rods with a high voltage and negative charge
2-dust particles gain electrons and become negatively charges
3-dust particles induce a charge on earthed metal plats (negatively charged dust particles repel electrons on the plate, so the plate becomes positively charged)
4-dust particles are attracted to metal plates, where they stick to form larger particles
5-when heavy enough, particles fall off plates or are knocked off by a hammer
6-dust falls to bottom of chimney and can be removed
-so gases coming out of the chimney contain fewer smoke particles

Question 13

How is static electricity used in defibrillators?

Answer 13

-beating of heart is controlled by tiny electrical pulses inside your body, so an electric shock to a stopped heart can make it start beating again
-defibrillators used to shock a heart back into operation
-consists of two paddles connected to power supply
1-paddles placed firmly on chest of patient to get good electrical contact
2-defibrillators charged up
3-everyone moves away except operator who holds insulating handles (so only patient gets shock)
4-charge passes through paddles to the patient to make their heart contract

Question 14

What do electrically charged objects attract?

Answer 14

-small neutral objects placed near them

Question 15

Explain how it is only electrons that move in static electricity?

Answer 15

• charges do not move

- it is electrons that move to cause charges

Question 16

What happens if enough a static charge builds up and what needs to be done about this?

Answer 16

• a big static charge can suddenly move and cause sparks or shocks that can be dangerous
• a charged conductor can be discharged safely by connecting it to earth with a metal strap
• this is earthing
• electrons flow down strap to ground if charge is negative and flow up strap from ground if charge is positive

Question 17

Why are insulators easily charged?

Answer 17

-electrons in an insulator cannot more freely like electrons in a conductor, so it is easier for their electrons to be scarped off and dumped on something else

Question 18

Where are static charges big problems?

Answer 18

• places where sparks can ignite inflammable gases

- places where there is a high concentration of oxygen (e.g. hospital operating theatre)

Question 19

What are precipitators used for?

Answer 19

-to remove smoke (which is made of tiny particles) created by factories and power stations