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# Static Electricity Forces

by Ron Kurtus (15 February 2009)

Static electricity is the buildup of electrical charges on the surface of materials. There is a force of attraction between opposite electrical charges and a force of repulsion against like electrical charges. If one object has a buildup of electrical charges and another object is neutral, the charged object will be attracted to the neutral one. These effects can be simply demonstrated.

Questions you may have include:

• How do objects attract each other?
• How do object repel each other?
• When is a charged object attracted to a neutral one?

This lesson will answer those questions. Useful tool: Units Conversion

## Opposite charges attract

The electric field moves from positive (+) electrical charges to negative (−) charges. (Plus to minus is a convention that was decided upon to help explain the fields.)

There is an electrical force that causes positive (+) electrical charges and negative (−) charges to attract each other. This can happen on a small scale, where a single electron is attracted to a positive charged ion.

In the case of static electricity, when one object has an excess of ions or atoms that have a positive charge on its surface and another object having an excess of electrons or of ions that have a negative charge on its surface, the two objects will attract toward each other.

Objects with opposite static electrical charges attract each other

You can see this force in action with static cling in clothes.

## Like charges repel

Similarly, when two objects have a buildup of like electrical charges on their surfaces, the electrical force causes them to repel each other.

A demonstration of like charges repelling can be seen by using two pith balls hanging on separate strings. A pith ball is a small ball made of a very light weight material. You can even use a small ball of paper to do the demonstration.

When the balls are given the same static electric charge, they will repel each other. A convenient way to give them the same charge is to tie the two strings to a single string and apply a static electric charge to that string.

Pith balls with the same static electric charge will repel each other

You can see this force in action when you have fly-away hair.

## Charges can attract to neutral item

An interesting phenomenon is that an object with an excess of static electric charges will attract an apparently neutral object. This can be seen by rubbing a balloon on some material to give it a charge and then sticking it to the wall.

Charged balloon sticks to neutral wall

The reason this works is because of what is called electrostatic induction. There are some free opposite charged atoms in the wall material. Thus, the wall is not completely neutral. But the number of available charges is not great. If the wall had been given opposite static electrical charges, the balloon would stick much better.

For some materials, such as a slate blackboard, the balloon will not stick at all.

## Summary

Objects static electrical charges will attract. Objects with like static electrical charges will repel each other. If one object has a buildup of electrical charges and another object is neutral, the charged object will be attracted to the neutral one.

Use your knowledge of static electricity to benefit mankind

## Resources and references

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Static Electricity Resources

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