1. Charging and Discharging Objects
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2. Objects can become charged by contact and by induction.
Key Ideas
Objects can become charged by contact and by induction.
Charged objects can be discharged by sparking and by grounding.

3. How Can Objects Become Charged and Discharged?
Why might you get a shock when you walk across a carpet in wool socks and then touch a metal door handle?
The charge you have built up on your body can easily be discharged (released) into objects such as a metal doorknob.
Why do you think the spark jumps to the doorknob?

4. Electroscope
An electroscope is a device that allows you to test whether an object is charged.
The main parts of an electroscope are a metal ball, a metal rod, and metal leaves.
The ball, rod, and leaves are all conductors.
When the metal leaves move apart, you know that they are charged.

5. What is charging by Contact?
Charging by contact occurs when you give a neutral object a charge by touching it with a charged object.
The image on the left shows an electroscope being charged by contact.
The leaves of the electroscope repel each other when they have the same charge.

6. What is Charging by Induction?
Charging by induction occurs when a neutral object becomes charged by a charged object that is brought near to it but does not touch it.
The negatively charged rod repels the negative charges in the ball, and they move to the leaves.
This leaves the ball positively charged.
No charges are transferred from the rod.

7. Charged objects can be discharged by sparking and by grouNding
The negative bottoms of the clouds induce a positive charge on the ground and objects on the ground.
When the attraction between charges on the bottom of the cloud and the charges on the ground are great enough, charges jump between the cloud and the ground, creating a lightning bolt.

8. How Grounding Discharges an Object
Grounding involves connecting a conductor to Earth’s surface so that charges can flow safely to the ground.
Fuelling trucks are grounded to avoid sparks igniting gasoline and metal rods protect buildings from lightning strikes.

9. Conductors and Inuslators
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10. Key Ideas
I will learn about the differences between conductors and insulators.

11. Electrostatic Series
The items at the top of the list tend to lose electrons and become positive, while the items at the bottom of the list tend to gain electrons and become negative. .
Glass
Wool
Cat Fur
Human Hair
Calcium
Lead
Silk
Cotton
Ebonite
Plastic
Copper
Nickel

12. What are Conductors?
In some objects, the charges can move away from each other.
In solid objects, only the negative charges can move.
In liquids, both positive and negative objects can move.
Conductors are materials in which electrical charges move freely.
Conductivity is an indication of how easily charge move within a material.

13. What Are Insulators?
An insulator is a material which electrical charges cannot move easily.
Which part of this cord is a conductor and which part is an insulator?
Why do you think it is built this way?

14. Review What is the type of charge that can move only in a solid?
Explain how objects can become charged by friction, contact and induction.
What are the differences between a conductor and an insulator?
Give an example of each.
Why would a stream of neutral water bend towards a negatively charged piece of plastic?