History:

A. Scientist Charles Dufey: Invisible fluid (called charge) transfer from one object to another during the process of rubbing.

2 invisible fluid transfer take place:

First fluid transfer cause the effect of attraction.

Second fluid transfer cause the effect of repulsion.

B. Scientist Benjamin Franklin: Only one invisible fluid (called charge) transfer between rubbed objects.

Excess of fluid: Positively Charged.

Deficit of fluid: Negatively Charged.

C. Scientist Charles Coulomb: Measure the force generated between 2 electrically charged object using a device called 'torsional balance'.

1 Coulomb charge = 0.625 x 10^19 elementary charge.

D. It was discovered much later that this “fluid” was actually composed of extremely small bits of matter called electrons, so named in honor of the ancient Greek word for amber.

Experiments:

1. Material Required: Comb, small cut pieces of paper.

Procedure: Rub the comb in your hair and then bring it close to the paper pieces.

Observation: ___________________________________________________________________