Question 26.2: Photon Mass Use the fact that the electromagnetic force acts...

Essential College Physics

Photon Mass

Use the fact that the electromagnetic force acts over an infinite distance to predict the photon’s mass.

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As shown in Equation 26.2, the mass of a mediating particle varies inversely with the range of the interaction:

$m=\frac{h}{2 \pi R c}$ (Mass of force-mediating particle; SI unit: kg) (26.2).

$m=\frac{h}{2 \pi R c}$ .

where m is the mass of the mediating particle and R is the range. For the electromagnetic force, the range is infinite. Therefore, the mass of the mediating particle (the photon) should be zero.

REFLECT This prediction agrees with observation. You know from Chapter 20 that the photon’s mass is zero.

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