Electrons are emitted from an electron gun at almost zero velocity and are accelerated by an electric field E through a distance of 1.0 m.
Electrons are emitted from an electron gun at almost zero velocity and are accelerated by an electric field E through a distance of 1.0 m. The electrons are now scattered by an atomic hydrogen sample in ground state. What should be the minimum value of E so that red light of wavelength 656.3 nm may be emitted by the hydrogen ?
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The given wavelength in Balmer series.
The first line, which requires minimum energy is from n1 = 3 to n2 = 2.
The energy should be equal to the energy required for transition from ground state to n = 3.
i.e. E = 13.6 [1 – (1/9)] = 12.09 eV
Minimum value of electric field = 12.09 v/m = 12.1 v/m
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