A gas discharge tube glows when a high voltage is applied because
Correct answer: B. accelerated electrons collide with gas atoms, exciting them, and the atoms then emit light as they return to lower levels
- A. the gas burns
- B. accelerated electrons collide with gas atoms, exciting them, and the atoms then emit light as they return to lower levels
- C. the glass becomes hot
- D. the gas is compressed
Explanation
Electrons accelerated by the field transfer energy to the atoms in collisions, lifting electrons to higher levels, and the light appears when they fall back. Neon gives its familiar red because of its particular set of energy levels, while sodium vapour gives yellow. Nothing is burnt, and the tube can run indefinitely because the gas is not consumed.
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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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