A photon of wavelength 900nm behaves like a particle of mass______________?
Correct answer: C. 2.46 x 10^-36kg
- A. 5.53 x 10^-36kg
- B. 0 kg.
- C. 2.46 x 10^-36kg
- D. 1.84 x 10^-44kg
Explanation
A photon has energy E = hc/λ, so its mass-equivalent is m = E/c^2 = h/(λc). Substituting h = 6.626 x 10^-34 J s, λ = 900 x 10^-9 m, and c = 3.00 x 10^8 m s^-1 gives m = 6.626 x 10^-34 / [(900 x 10^-9 m)(3.00 x 10^8 m s^-1)] = 2.45 x 10^-36 kg, approximately 2.46 x 10^-36 kg. The likely mistake is choosing 0 kg because a photon has zero rest mass, whereas this question asks for mass-equivalent based on its energy.
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About Photons and the Particle Model of Light
The particle model treats light as photons with energy E equals hf and momentum related to wavelength. Questions involve the photoelectric effect, work function, threshold frequency, stopping potential and photon energy, while distinguishing particle behaviour from the wave description of interference and diffraction.
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