1. Charging by contact
Friction, Conduction

2. Learning goals We are learning to charge objects by conduction.
We are learning to use two types of electroscopes.
We are identifying conductors and insulators.

3. Charging by conduction
charging an object by contact with a charged object
electrons transfer from a charged object into a neutral object
neutral object gains same type of charge as object that touched it

4. grounding symbol for grounding
removing a charge from an object by connecting it with a conductor to the ground
electrons flow into the Earth so the object becomes neutral
since the Earth is so large, adding these electrons does not change it
symbol for grounding

5. Electroscopes

6. Electroscope a device that detects the presence of charge
there are two types
Metal leaf
Pith ball

7. consists of a metal sphere, rod, and leaves
(1) Metal Leaf
consists of a metal sphere, rod, and leaves
sphere
rod
leaves

8. Metal Leaf cont’d… - when the leaves become charged they repel
this happens when a charged object either touches or comes near the electroscope - +

9. How it Works
when a charged object is brought near or touches the ball of the electroscope, the electroscope becomes charged
because the electroscope is a conductor the charge will spread all over
when the leaves become charged they repel

10. Negatively Charged Object Positively Charged Object
(2) Pith Ball
a ball of pith hanging on a string
can test for presence of charge and type of charge by:
bringing object close to neutral pith ball
if the object is charged the pith ball will be attracted to it
Negatively Charged Object +
Positively Charged Object - - - - - - - + - - + + + - - - + - + - - +

11. Learning goals We are learning to charge objects by conduction.
We are learning to use two types of electroscopes.
We are identifying conductors and insulators.

12. Lab
Testing for Conductors and Insulators