This is a basic introduction to charging processes. It has some nice electroscope animations that I spent a lot of time creating. Please comment if you would like to see more of my physics PowerPoints - especially if you have specific requests!

1. Restless Electrons Mechanisms for Transfer of Charge

3. Conductive Properties of Solids Conductors allow charge to flow through them easily high conductivity Insulators inhibit charge flow high resistivity rubber sili con wood pure water metals special metal alloys SUPER CONDUCTORS SEMI INSULATORS CONDUCTORS CONDUCTORS sea water

4. Friction This works best when two INSULATORS are rubbed against one another

5. Conduction Negative To Neutral - - Excess electrons exert repulsive forces on one another, causing them to move apart as much as possible BOTH now have the same charge!

6. Conduction Positive To Neutral + + BOTH now have the same charge! Electrons in the neutral object experience an attractive force. They neutralize some of the positive charge, leaving both with a lack of electrons

7. Induction Negative To Neutral Polarization + - - Excess electrons exert force against nearby electrons in the neutral object

8. Induction Positive To Neutral Polarization + - + Electrons in the neutral object experience an attractive force, which pulls them closer to the charged object

9. Grounding Since the Earth is so large it can equalize charges from other objects very easily The Earth can equalize charge by: absorbing excess electrons from negatively charged objects giving free electrons to positively charged objects In either case, grounding a charged object makes it neutral One symbol that is often used to show that something is grounded is:

10. Electroscope - - - - - - - An electroscope is a device that detects CHARGE When the scope is CHARGED , the LEAVES at the bottom will REPEL one another The charged LEAVES exert force on one another, forcing them apart

11. Electroscope – negative cond. - - - - - - - Step 1 Negative rod touches neutral scope Step 2 Electrons spread out and charge plates Step 3 Scope is now negatively charged Step 4 Scope is grounded allowing electrons to escape Step 5 Scope is once again neutral – excess electrons are gone

12. Electroscope – positive cond. + + + + - - - - - - Step 1 Positive rod touches neutral scope Step 2 Electrons leave scope because they are attracted to the positive rod Step 3 Scope is now positively charged Step 4 Scope is grounded – electrons from the ground are attracted to the positive scope Step 5 Scope is once again neutral – balanced charge is restored

13. Electroscope – negative ind. - + - - Step 1 Negative rod brought near grounded scope Step 2 Scope polarizes as electrons at the top try to move away from the charged rod. Step 3 Rod is removed – electrons are attracted back to the top and “re-neutralize” the electroscope.

14. Electroscope – positive induction + - - Step 1 Positive rod is brought near neutral electroscope Step 2 Electrons from the bottom of the electroscope are attracted to the positive rod – get pulled up. The leaves get a positive charge on them. Step 3 Rod is removed. Electrons are attracted back into the leaves by the protons, making the electroscope neutral again. + +

15. Electroscope – ind. with ground - + - + + - - Step 1 Negative rod brought near grounded scope Step 2 Excess electrons from the rod force electrons from the scope into the ground. Step 3 Ground is removed while the rod is still nearby, keeping electrons from re-entering the scope Step 4 Scope now has a charge that is opposite to the charge on the rod Step 5 The rod is taken away and the positive charge remains on the scope

16. Electroscope – ind. with ground + - - - Step 1 Positive rod is brought near grounded scope Step 2 Electrons from the ground are attracted to the positive rod Step 3 Ground is removed, while the rod is still nearby, pulling on electrons and keeping them from escaping Step 4 Scope is now negatively charged – the opposite charge as that of the rod Step 5 Rod is taken away and the negative charge remains on the scope