Practice question · Sort into groups
Sort each pair of charged objects by the direction of the force between them.
Groups: They repel · They attract
- A proton and an electron
- Two negatively charged balloons
- A positively charged rod and a negatively charged sphere
- Two protons
- Two electrons
Hints
- Like charges repel; opposite charges attract.
- Two negatives are still LIKE charges, even though both are negative.
Show the answer
They repel: Two protons, Two electrons, Two negatively charged balloons
They attract: A proton and an electron, A positively charged rod and a negatively charged sphere
Why
Only pairs of opposite sign attract. The item that catches people out is the two negative balloons: 'both negative' feels like it should be attraction by analogy with magnets' north and south, but two negatives are like charges and they push apart.
Practise Electromagnetism
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