Electric Force

Goal: To investigate the electrostatic interaction between various objects.

Theory: When objects are rubbed against each other they acquire electric charge. Objects of the same electric charge attract and objects of opposite charges repel.
Preliminary Setup
- You need:
  - Scotch Tape, paper, glass bottle, soda can
  - You will be supplied with: plastic and wooden pieces; cotton, wool and silk cloth; teflon tube
- Experimental setting:
  - Cut 4 pieces 15-cm-long scotch tape. Fold one end to prevent it from sticking.
  - Stick two pieces directly onto smooth surface. Write "X" on the folded end.(Both pieces are stuck on the table surface.)
  - Stick the third tape on the table as well. Write "B" on its folded end.
  - Stick the fourth tape on top of the "B" tape. Write "T" on its folded end.

Activity 1: Determine how different objects interact through the electrostatic force.

Determine the interaction between the various scotch tapes.
- Pull the two "X" pieces abruptly off the top of the table. Bring them close to each other.
  Do they repel or attract each other? Answer:___________
  Does it matter which side faces which side? Answer:_____________
- Pull the "T" and "B" pieces off the table together. Using both hands, separate the tapes abruptly. Bring them close to each other.
  Do they repel or attract each other? Answer: _________
  Does it matter which side faces which side? Answer:__________
Stick the "T" and the "B" tape to a surface, so that 10 or more cm of the tapes are hanging freely in the air. Make sure the tapes are sufficiently far so that they do not interfere with each other. At any time if you notice the tapes are beginning the loose their charge, you can recharge them by repeating steps II.2.iii-II.2.iv.

For each of the following objects, determine whether they are repelled or attracted by tape "B" and tape "T". Record your data in your data table.

Record your data in the following table. Write down "attract" or "repel" according to your observations.


Object	"T" tape	"B" tape
"T" tape
"B" tape
"X" tape
plastic rubbed with cotton
wood rubbed with cotton
wood rubbed with the blue towel
wood rubbed with woold
wool rubbed onto wood
teflon rubbed with fur/wool
glass rubbed with silk
balloon rubbed with cotton

Object "T" tape "B" tape soda can paper sheet human hand

Results.
- Arrange the objects in two categories according to their charge.
  
  "T" charge "B" charge
- What is the charge of the soda can? Answer:____________
- What is the charge of your hand? Answer:______________

Last modified: Tue Jan 27 14:22:51 Eastern Standard Time 2009