Modern Physics 7 Question 69
17. In a Frank-Hertz experiment, an electron of energy
(Main 2019, 12 Jan II)
(a)
(b)
(c)
(d)
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Solution:
- Minimum wavelength occurs when mercury atom deexcites from highest energy level.
Wavelength of photon emitted in deexcitation is
NOTE
Frank-Hertz experiment was the first electrical measurement to show quantum nature of atoms. In a vacuum tube energatic electrons are passed through thin mercury vapour film. It was discovered that when an electron collided with a mercury atom, it loses only a specific quantity (
