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Question
Choose the correct option.
The equation E = pc is valid ______.
Options
For all sub-atomic particles
is valid for an electron but not for a photon
is valid for a photon but not for an electron
is valid for both an electron and a photon
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Solution
The equation E = pc is valid for a photon but not for an electron.
Explanation:
The equation E = pc is the extension of Einstein’s mass-energy relation extended by Paul Dirac.
• The equation E = pc is valid when the rest mass of the particle is zero.
• The rest mass of the photon is zero, but the electron is not zero. Therefore, E = pc is not valid for the electron, but valid for the photon.
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