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An electron with speed υ and a photon with speed c have the same de-Broglie wavelength. If the kinetic energy and momentum of electron are E e and p e and that of photon are E ph and p ph respectively. Which of the following is correct ?

1. υ = c 2 E E ph e
2. υ = 2 c E E ph e
3. υ = c 2 p p ph e
4. υ = 2 c p p ph e

Correct answer: υ = 2 c E E ph e

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