The frequency of incident light falling on a photosensitive plate is doubled, then the maximum kinetic energy of the emitted photoelectrons will become:
Correct answer: B. More than 2 times the earlier value
- A. 2 times the earlier value
- B. More than 2 times the earlier value
- C. Less than 2 times the earlier value
- D. Unchanged
Explanation
Initial KE = h(v - v₀). Doubled frequency: KE₁ = h(2v - v₀) = 2h(v - v₀) + hv₀ = 2KE + hv₀, which is more than doubled due to the hv₀ term.
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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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