Charging by Contact: CONDUCTION 11.2 This method of charging objects involves contact between a charged object and a neutral object.

If the charged object is negatively charged, electrons will move onto the neutral object. If the charged object is positively charged, electrons from the neutral object will move onto the positively charged object. The negatively charged rod is moved toward a neutral pith ball electroscope so that both objects touch While the two objects are touching, some electrons from the rod move onto the pith ball. The pith ball now has a negative charge.

Ex #1: A negatively charged rod touches a neutral pith ball.   negative neutral

e- Ex #1: A negatively charged rod touches a neutral pith ball.   e- negative negative neutral The _____________ on the negatively charged rod repel each other and jump from the _________ to the ______________. The negative rod has shared its electrons with the pith ball and they are now both ________________ charged. electrons rod pith ball negatively

*** The neutral object gets the ___________ charge as the charged object since the charged object shares its charge with the neutral object.   same

Ex #2: Show the charge distribution and the position of the leaves of the metal-leaf electroscope before and after being touched by a positively charged rod.   Neutral Positive Before After

Ex #2: Show the charge distribution and the position of the leaves of the metal-leaf electroscope before and after being touched by a positively charged rod.   Neutral Positive Positive Before After

When the positively charged object touches the neutral electroscope, ______________ jump from the __________________ to the ___________ (because of the attraction between electrons and protons). The electroscope is now ____________________ charged because it ___________ electrons. Since it is charged, its leaves will __________________.   electrons electroscope rod positively lost repel / separate

Grounding When a charged object touches a large neutral object such as Earth, the charged object becomes grounded and loses its net charge. If the charged object was positively charged, electrons from the large neutral object move toward the charged object. If the charged object was negatively charged, electrons move away from the charged object toward the neutral object.

Hand is negatively charged. Grounding Step 1 Hand is negatively charged. Faucet is neutral.

Grounding Step 2 When the hand is close to the faucet, some electrons from the hand move toward the faucet and create an electric discharge.

Grounding Step 3 After grounding, the hand loses its negative charge. The extra electrons go into Earth.

Symbol for Grounding

Worksheet: Charging by CONDUCTION Figure 1 e- e- Neg

Worksheet: Charging by CONDUCTION Figure 2 e- e-

Worksheet: Charging by CONDUCTION Figure 2 e- e- Pos

Homework p. 477 # 3-8