# Physics Topic One - Static and Current Electricity

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• Created by: Fawnflys
• Created on: 19-04-15 15:01
What happens to electrons as two insulating materials are rubbed together
the electrons will be scrapped off one material and dumped on another material
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What does friction cause the charges of the materials to do?
A positive charge will be left on one of the materials while a negative charge will be left on the other.
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When electrons move FROM the object what charge does it have?
Positive
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When electrons move ONTO the object what charge does it have?
Negative.
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When two object have opposite charges what happens?
They are attracted to each other
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When two objects have the same charge what happens?
The objects repel each other.
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What happens to the force of the charges as they get further apart?
They get weaker.
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Describe what happens when a polythene rod has been rubbed with a duster.
The electrons move onto the rod from the duster, which now has a positive charge, while the polythene rod has a negative charge.
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Describe what happens when a Acetate rod is rubbed with a duster?
The electrons move from the acetate rod onto the duster, giving it a negative charge while the acetate rod now has a positive charge.
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Why does synthetic clothing crackle when rubbed over each other?
The electrons get scrapped off, leaving static charges on both parts, leading to an attraction. Little sparks occur as the charges try to rearrange themselves.
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How can static electricity cause you to be shocked by a car?
charge can build up on your cloths due to rubbing on the car seat, the friction then causes electrons to be scrapped off, when touching the metal door you may then get a shock.
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How can static electricity cause shocks from door handles?
You can receive a small shock from a metal door handle when wearing insulating shoes and walking on a nylon carpet causing a transfer of electrons building up on your body.
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How can you make a balloon stick to a wall after rubbing against you hair or clothes and what happens to the charges?
Electrons will be transferred to the balloon from you hair giving the balloon a negative charge. the negative charges on the balloon repel the negative charges on the wall leaving a positive charge on the surface attracting the balloon.
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Explain the term 'induction'?
Using charged objects to force charges in an uncharged object to move.
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How can a charged comb pick up paper?
Electrons will be transferred to the comb and will become negatively charged, then the non-charged paper can be picked up by the comb due to induction.
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How is lightening caused?
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 is negatively charged creating a huge voltage and a big spark.
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What are bikes and cars painted with?
Electrostatic paint sprayers
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How do Electrostatic paint sprayers work?
You get a fine spray of paint as the object is given an opposite charge to the spray gun so the car attracts the paint, as the paint has the same charge the droplets repel each other leaving a fine spray.
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What are the benefits of using an electrostatic paint sprayer?
They give an even coat and hardly any paint is wasted. Any parts of the car pointing away from the spray gun still receive paint so no shadows are formed.
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How can electrostatic charges cause problems when filling up a car?
As fuel flows out of the filler pipe, static charge can build up. This can lead to a spark causing an explosion in dusty and fumey places, like a petrol station.
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How can sparks be prevented?
By connecting a charged object to the ground using a conductor.
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How does 'earthing' work?
The electrons flow down the conductor to the ground if the charge is negative and flow up from the conductor is the charge is positive, preventing sparks.
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What is Current?
The rate of flow of charge around a circuit.
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Why are metals good conductors?
They have free electrons which are able to move.
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What is the formula for CHARGE?
Charge = Current X Time
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What type of current do cells and batteries supply?
Direct Current
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What is Direct current?
Current that flows in only one direction.
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How can we look at a direct current trace?
On an Oscilloscope.
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Why is the line of direct current always straight?
Because a direct current source is always the same voltage.
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What is alternating current?
Current that changes direction
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Where is alternating current used?
In mains electricity.
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## Other cards in this set

### Card 2

#### Front

What does friction cause the charges of the materials to do?

#### Back

A positive charge will be left on one of the materials while a negative charge will be left on the other.

### Card 3

#### Front

When electrons move FROM the object what charge does it have?

### Card 4

#### Front

When electrons move ONTO the object what charge does it have?

### Card 5

#### Front

When two object have opposite charges what happens?