Select true photon statements: (I) E = hν; (II) photon speed in free space is c; (III) momentum p = hν/c; (IV) total energy and momentum are conserved in photon–electron collisions; (V) a photon has positive charge.
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Question

Select true photon statements: (I) E = hν; (II) photon speed in free space is c; (III) momentum p = hν/c; (IV) total energy and momentum are conserved in photon–electron collisions; (V) a photon has positive charge.

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G1 Physics · Accepted Answer

A photon has energy E = hν and momentum p = E/c = hν/c, travels at c in vacuum, and interactions conserve total energy and momentum. A photon has zero charge, so V is false. I–IV are true. Answer: A.