Which photon is traveling with the largest speed in a vacuum?
Correct answer: D. All photons move with the speed of light
- A. Gamma photon
- B. Visible light photon
- C. Infrared photon
- D. All photons move with the speed of light
Explanation
A vacuum refers to the space in which no matter is present. Therefore, any object moving inside such space faces no frictional forces and so will naturally move faster.The reason here is that in a vacuum, the photons of any EM wave travel at equal speeds. According to this formula, the product of frequency and wavelength remains constant for a given photon which is the speed of light.c= fλc=3.00 × 108 m/sc=3.00 × 108 m/sRegardless of frequency or wavelength (which is what distinguishes each option from the other), the speed of the photon will be the same. However, the propagation speed through anything with a refractive index ( or optical density ) is slower than this. Generally speaking, longer wavelengths travel through some mediums faster than others.
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About Dawn of Modern Physics
Classical physics cannot explain blackbody radiation and related observations, leading to Planck’s quantum theory, in which energy is emitted or absorbed in discrete packets. Photons provide the particle model of light, with energy and momentum linked to frequency and wavelength, including the photoelectric effect and its threshold frequency.
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