In what ways do photons resemble other particles such as electrons? In what ways do they differ? Do photons have mass? Do they have electric charge? Can they be accelerated? What mechanical properties they have?

Expert Answers

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High energy photons such as gamma rays have a wavelength of about 10^-11 metres. They can be thought of as particles of this size.

The classical electron radius is about 10^-15 metres. So their size isn't comparable.

Photons have no charge, electrons are charged. They have no mass but an electron is about 9 x 10^-31 kg.

Photons can't be accelerated they only ever travel at the speed of light. Electrons can be accelerated (as in a cathode ray tube).

Photons do have momentum but not in the usual mechanical sense.

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