Charged pen and aluminium foil

In summary, the problem involves a charged plastic pen and an uncharged aluminum foil disk. The goal is to determine how close the pen must be moved to the foil in order to pick it up. One approach is to treat the foil as a capacitor and use the formula for electric field to calculate the charge on the foil. Another approach is to use the formula for density and the force of gravity to calculate the distance at which the pen can pick up the foil. Further guidance and clarification is needed to solve the problem correctly.
  • #1
luckyducky
5
0

Homework Statement


A clear plastic pen of length 14.5 cm is rubbed with wool. The charged plastic pen is held over a small uncharged disk shaped piece of aluminium foil of diameter 0.5cm. How close you must move the pen to the foil in order to pick up the foil?



The Attempt at a Solution



Ok I thought I would let the disk be a diople and let the pen be a point charge but nothing worked. Please explain to me how I should do this question.

Thank you very much
 
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  • #2
You migth want to study the forum rules. You MUST attempt the problem, and tells us what relations and formulas you know.
 
  • #3
This is what I did?

Ok this is what I did but don't know whether it is right or not:
E = 1/(4 pi epslon) * Q/d^2 is the electric field of the pen

I said that the aluminium foil works like a capacitor therefore:
(qA)/epsilon - 1/(4 pi epslon) * Q/d^2 = 0 also Q=10 nanoC the charge of the pen

then I can figure out the charge of the foil on one side I think(I hope this is right)

Electricfield of disk = ((Q/A)*(s/R))/2epsilon where s=thickness of the disk
also m=dV is the formula for density, but is V= pi r^2 s
then if the above is right we know F = mg
F = ((Q/A)*(s/R))/2epsilon m = D pi r^2 s
therefore:
((Q/A)*(s/R))/2epsilon = D pi r^2 s g

But is this even right, I really need you guys to help me please HELP me !
 

1. What is a charged pen and aluminium foil?

A charged pen and aluminium foil is a simple experiment that demonstrates the transfer of static electricity. It involves using a charged pen to create an electric charge on a piece of aluminium foil.

2. How does a charged pen and aluminium foil work?

When you rub a pen against your hair or clothing, it becomes charged with static electricity. When you touch the charged pen to a piece of aluminium foil, the electric charge causes the foil to attract and repel the pen, making it move and stick to the foil.

3. What materials do I need to do a charged pen and aluminium foil experiment?

You will need a pen, a piece of aluminium foil, and a source of static electricity such as your hair or a wool cloth. You may also want to use a ruler or other object to help move the foil and a table or other flat surface to work on.

4. What is the purpose of a charged pen and aluminium foil experiment?

The purpose of this experiment is to demonstrate the principles of static electricity and how electric charges can be transferred from one object to another. It is also a fun and easy way to explore the properties of electricity.

5. Can I use other materials besides a pen and aluminium foil for this experiment?

Yes, you can use other materials such as a plastic comb, a balloon, or a spoon to create static electricity and try the experiment with different objects. However, the most important thing is to have a source of static electricity and a light, thin material to see the effects of the electric charge.

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