Concepts: Electric Charges

Postitive/Negitive Charges

Forces between charges

Static Electricity

Coulomb's Law: His law represents (in equation form) the magnitude of the electric forces between two electrical charges.

F=k x q1 x q2/d2  k is contstant

q1=>charge one

q2=>charge two

d=>distance between charges

Materials:

• String
• Copper Wire
• Piece of wool
• 2 plastic strips
• Plastic bag

Teqhnique:

I Preparation

A.Hand a string from the ceiling.

B.Attach a piece of copper wire to the end of the string.

C.Bend both ends of the wire upward.

II. Charging the plastic strips.

A.To attract one another

??????? 1.Rub the tip of one plastic strip with the plastic bag.

??????? 2.Place this plastic strip across the sespended copper wire.

??????? 3.Rub the tip of the other plastic strip with the wool.

??????? 4.Bring the tips close together to observe the attraction.

??? B. To repel one another

??????? 1.Rub both the tips of the pl;stic strips with the palstic bag.

??????? 2.Place one strip across the copper wire.

??????? 3.Bring the tips close together (without touching) to observe them repelling one another.

Key Ideas:? Electric charges are of two types (+,-)? Law of charges:? Like charges repel, and unlike charges attract. ? Static Electricity:? is a buildup of an electric charge on an object. ? Electric discharge:? is the process of balancing electrical charges.