3. The magnitude of the charge on the proton is equal to the charge on the electronThe magnitude of the charge on the proton is equal to the charge on the electron An object is electrically charged if it has a different number of protons and electronsAn object is electrically charged if it has a different number of protons and electrons Atoms are electrically neutral: they have the same number of protons as electronsAtoms are electrically neutral: they have the same number of protons as electrons

4. Law of Conservation of Charge: the net amount of charge produced in any process is zero. The positive charges on a conductor cannot move, but some of the electrons can. The SI unit of charge is the coulomb (C) The smallest unit of charge possible is the elementary charge, 1.60 x 10 -19 C (on data sheet) One electron has a charge of - 1.60 x 10 -19 C (on data sheet)

5. All charges are a whole number multiple of the elementary charge The charge of one proton is 1+ (1 positive elementary charge) An alpha particle Helium nucleus Charge: 2+ (2 elementary charges) Symbol:  2+

6. CHARGING BY FRICTION When 2 different substances are rubbed together, electrons can be transferred from 1 substance to another Some materials hold onto electrons more tightly than other materials One substance gains electrons becoming negatively charged. The other substance loses electrons and becomes positively charged The total amount of charge doesn't change (charge is conserved)

8. ELECTROSCOPE Used to detect the presence of an electric charge The further apart the leaves, the greater the charge. leaves

9. INDUCED CHARGE SEPARATION  Electrons in the leaves are attracted to the head of the electroscope, leaving the leaves positive The separation of charge in the electroscope is caused by the charge on the rod  The electroscope is still neutral, when the rod is removed, the extra electrons in the head return to the leaves

10. CHARGING BY CONTACT (Conduction) When a charged object touches another object, the charges are shared equally Negative object Neutral object e-e- e-e- e-e- e-e- e-e- A neutral object that has been charged by contact has the same sign as the charged object + + + + e-e- e-e- e-e- negative

11. If a positively charged object touches a neutral object, some of the free electrons from the neutral object will move to the positively charged object Positive object Neutral object e-e- e-e- + + + + + + + + positive e-e- e-e-

12. Electroscope Animation

13. Example A sphere with a charge of 3.0  C is touched to a sphere with a –9.0  C charge. When the spheres are separated, what are the charges of each sphere? (+3.0  C) + (-9.0  C) 2 = -3.0  C

14. CHARGING BY INDUCTION If a negatively charged rod is brought near a conductor that is connected by a wire to a much larger object, electrons from the conductor will move along the wire to the larger object 1) When the wire connecting the electroscope and the other object is broken, the electroscope is left with a positive charge 2) An object charged by induction takes on the opposite charge to that of the charging rod

15. e-e- e-e- + + e-e- e-e- e-e- e-e- e-e- + + + + e-e- e-e- (-) (+) (-) Mr. Ouellette performs an unethical experiment on an unsuspecting Mrs. Labbe...