Electricity
Electricity­ the movement of charged particles (electrons) through materials. (this can be used as a valuable energy resource for humans)
Two Main Types:
Static electricity­ gathers in one place.
Current electricity­ moves from one place to another.
Feb 9­7:14 PM
The Atom
­ All matter is made up of tiny particles called atoms. (fig. 7.2, pg. 230)
­ In the center of the atom you find the nucleus.
­ The nucleus has both neutrons and protons, the nucleus has a positive charge.
­ Surrounding the nucleus are lighter, negative charged particles called electrons.
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If the number of electrons in an atom is equal to the number of protons, we say the atom is neutral (uncharged).
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There are three types of charges an object can have:
1. Positive Charge ­
There are fewer electrons then protons and neutrons. Example­ An object or surface with 100 electrons and 200 protons/ 200 neutrons.
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2. Negative Charge
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There are more electrons then protons and neutrons. Example­ An object or surface has 500 electrons but only 300 protons/ 300 neutrons.
Feb 10­10:00 AM
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3. Neutral ­
There are an equal number of electrons, protons and neutrons. Example­ An object has 6 electrons, 6 protons and 6 neutrons.
Feb 10­10:01 AM
So do we understand how charges on objects change?
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Neutral objects can become positive charge.
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Neutral objects can become negative.
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Positively charged objects can become neutral.
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Negatively charged objects can become neutral.
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So what is static electricity again?
Static electricity is the build up of electric charge ﴾positive or negative﴿ as a result of some type of materials being rubbed together.
One object will loose some of its electrons while the other will gain some electrons.
﴾Note: Think about our balloon activity last class, or rubbing across carpet and touching a metal doorknob﴿
Man made lightning: The Van de Graaff generator
Feb 9­9:11 PM
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Static electricity occurs when two objects rub up against each other (friction) and there is a transfer of electrons. ­
One object gains electrons while the other loses electrons. ­
As well, static electricity is stationary and can only be on insulators.
Mar 19­1:12 PM
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Friction and the transfer of electrons
Electric Discharge:
when an object loses its electric charge (like when the balloon starts to fall off your head after you rubbed it against your hair at a birthday party). Feb 10­9:10 AM
Measuring Electric Charge: The Coulomb
Coulomb­ the unit of electric charge. 1 coulomb of charge is the addition or removal of 6.25 x 1018 electrons. One coulomb of electric charge passes through a 100 W light bulb every second. So when we look at the movement of electrons in a diagram we never draw the true number which are moving.
Feb 10­9:12 AM
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The Laws of electric charges:
(1) Opposites attract each other.
(2) Like charges repel each other.
(3) Charged objects attract neutral objects.
Feb 9­10:34 PM
Readings and Questions:
Pages 228­234
Questions:
Page 231 #'s 1,2,4,5,6 Page 234 #'s 1,2,4 Feb 9­10:41 PM
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