Like and unlike charges

The idea

There are two kinds of static charge, positive and negative; similar (like) charges repel each other, while opposite (unlike) charges attract each other.

Two balloons

Two balloons are rubbed with the same woollen cloth and brought near each other. They move away from each other.

What does this suggest?

• Similar charges repel each other
• Similar charges attract each other
• Charges do nothing

Pick the charges

Choose the charge on each balloon. Find when they repel and when they attract.

Like repel, unlike attract

Two similarly charged balloons moved apart. Balloons with opposite charges moved together. The two kinds of static charge are called positive and negative.

There are two kinds of static charge, positive and negative. Like (similar) charges repel each other. Unlike (opposite) charges attract each other.

• Charges | Force
• Positive and positive | Repel
• Negative and negative | Repel
• Positive and negative | Attract

Notes

There are two kinds of static charge: positive and negative. Like charges repel. Unlike charges attract.

Check yourself

Two similarly charged balloons …

A charged balloon and the woollen cloth it was rubbed with …

What are the two kinds of static charge called?

Which pair of charges attracts?

• attract each other. Like charges repel each other.
• repel each other — correct. Yes!
• do nothing. Like charges repel each other.
• repel each other. They have opposite kinds of charge, so they attract.
• do nothing. They have opposite kinds of charge, so they attract.
• attract each other — correct. Yes!
• Positive and negative — correct. Yes!
• North and south. North and south are magnet poles. Charges are positive and negative.
• Hot and cold. Hot and cold are about temperature. Charges are positive and negative.
• Two positives. Like charges repel.
• A positive and a negative — correct. Yes!
• Two negatives. Like charges repel.