static electricity. what is static electricity? static electricity is the build up of electrons on...
TRANSCRIPT
Static Electricity
What is Static Electricity?
• Static electricity is the build up of electrons on the surface of objects.
• This charge will stay on the surface until a contact allows it to transfer
Think back
• Electrons are negatively charged particles that can move from atom to atom.
• Protons are positively charged particles that cannot move
How do objects get Static Electricity?• e- can leave one atom and go to
another atom.
• The substance they vacate gets a (+) charge
• The substance they go to gets a (-) charge
Protons cannot move!!
• Static electricity is caused by the movement of the e-. p cannot move.
• While they have a (+) charge, they stay put.
How do objects get Static Electricity?• Usually, p and e- are the same, so the
object is neutral.• e- are usually transferred by friction.
• No matter what, when rubbing two objects together, one will become (+) and one will become (-)
Electron Affinity
• the tendency of a material to hold onto electrons.
• Some materials have a very strong hold on e-(plastic wrap), other materials do not (glass).
Electron Affinity
• Some materials with a very high e- affinity will steal e- from other atoms.
Gold
acetate
Electrostatic Series• A list of some materials listed in order of
their electron affinity.
• Top materials lose e- easily and will gain a (+) charge.
• Lower materials gain e- easily and gain a (-) charge.
• Important fact: e- are not lost! They are only transferred to another material
The Laws of Electric Charges• Objects with a like charge will repel • Objects with an unlike charge will attract• Neutral objects are attracted to charged objects
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How will these two react?
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How will these two react?
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How will these two react?
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How will these two react?
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The rubber balloon was rubbed onto the woolen sweaterThe balloon took the electrons from the sweater since rubber has a higher electron affinity than woolThe negatively charged balloon sticks to the positively charged sweater. The wall is neutral – equal number of electrons and protons
The negatively charged balloon is brought close to the wall. The electrons in the wall are repelled by the excess electrons in the balloon and they move away from the balloon leaving the part of the wall closest to the balloon positively charged. The positive wall and the negative balloon are attracted to each other and they stick.
Conductors and Insulators
• Conductors are substances that transfer e- very well. (metals are great conductors)
• Insulators impede the flow of e- (wood, plastic and rust are a few)
• Fair Conductor – transfers e-, but not that well. (human body, soil, water)
Q’s
• Pg 403 #1, 2, 3, 6, 7, 10, 12
Why dust sticks to your T.V.
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T.V.
Neutral dust particle
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