Charging Objects Electrically

Demo

Electroscope, Fur, Acrylic Rod

Concept Overview:

1. Friction may cause an object to become electrically charged.

2. Two kinds of charge exist - positive and negative (attraction and repulsion)

3. Conductors vs. Insulators (differences in ability to become charged)

Lecturer Procedure

Step(s) to Follow Expected Result
1. Charge rubber horse tail by running them through fur. Strands repel each other and spread out.
1. Charge each hanging balloon by rubbing it with the fur.

Balloons repeal each other.

Balloons attract stand rod.

1. Charge rubber rod with fur at tip away from hand.

2. Hold tip near balloons (as far from body as possible)

Balloons are repelled.

1. Flip end of glass rod with silk to charge it.

2. Bring glass rod near balloons.

Balloons are attracted to glass rod.

1. Charge top of free balloon with fur.

2. Place balloon, tie down, against ceiling.

Balloon remains on ceiling for hours.

1. Place sheet of paper on black board.

2. Rub paper with fur.

Paper will remain on board for hours.

1. Tear bits of paper (~0.25-0.5 in) and spread on lecture table.

2. Charge rubber rod.

3. Hold rod above paper bits.

Some will hop to rod, stay for a while, and then be repelled with vigor.

1. Rub one end of rubber rod with fur.

2. Place in rotating mount.

3. Charge second rubber rod with fur.

4. Bring rod 2 near charged portion of rod 1.

 Repulsion occurs (rubber rods have negative charge)

1. Rub one end of glass rod with silk.

2. Bring near charged end of rubber rod in rotating mount.

Attraction occurs. (glass rod has positive charge)

1. Charge electroscope 1 by touching it with the charged rubber rod (-).

2. Charge electroscope 2 by touching it with the charged glass rod (+).

3. Bring charged glass rod near each electroscope.

4. Bring charged rubber rod near each electroscope.

5. Rub metal rod (no insulating handle) with fur.

6. Bring metal rod near each electroscope.

7. Bring metal rod near rubber rod located in rotating mount.

8. Bring non-charged metal rod near both electroscopes and mounted rod

9. Repeat above steps with brass end of glass rod.                                                                                                                             

(3) Deflection of needle for electroscope 1 will decrease; deflection of needle for electroscope 2 will increase

(4) Results will be the reverse of step 3

(6) Deflection of each electroscope is decreased

(7) Attraction occurs

(8) Same results as step 7

(9) Negative charge is observed

Additional Apparatus:

For Rubbing: Fur, Silk, Wool                                                                     Rods: Rubber, Glass, Acrylic, Plastic, Metal

Fur, Silk, Wool                                                                  Rubber, Glass, Acrylic, Plastic, Metal

 

Rubber Horse Tail                                          Rotating Mount                                                Rubber Balloons

Rubber Horsehair suspended from ring stand                   Rotating Mount                        (not pictured)

Butane Lighter                                                                                                                       8.5x11" Printer Paper

Butane Lighter                                   (not pictured)

 

Identifier: 
E&M: ES - 001