Asked in Premeth Test 17 — Atomic Spectra (physics)Moderate

If the K.E of a free electron doubles, its de Broglie wavelength changes by the factor:

Correct answer: C. Option C

  • A. Option A
  • B. Option B
  • C. Option C
  • D. Option D

Explanation

The de Broglie wavelength of a particle is inversely related to its momentum, and momentum depends on the square root of kinetic energy. So, if the kinetic energy of a free electron doubles, its momentum increases by the square root of 2, and therefore its de Broglie wavelength decreases by a factor of 1 over √2.

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About Atomic Spectra

Atoms emit or absorb light at specific wavelengths because electrons occupy quantized energy levels and change levels by absorbing or releasing photons. The topic covers emission and absorption spectra, spectral series, hydrogen’s line spectrum, energy-level transitions, and the relation between wavelength, frequency and photon energy.

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