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Davisson and Germer experiment
Concepts tested here
- Accelerating potential
All Questions
2011 AIPMT-PRE 1 question
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In the Davisson and Germer experiment, the velocity of electrons emitted from the electron gun can be increased byIn the electron gun, electrons emitted by the heated filament are accelerated towards the anode by the potential difference V applied between the anode and the filament.
Energy gained: $\frac{1}{2}mv^2 = eV$, so $v = \sqrt{\frac{2eV}{m}}$
Thus $v \propto \sqrt{V}$: the velocity increases when the accelerating potential difference is increased.
Changing the filament current only changes the filament temperature and hence the number of electrons emitted, not their final velocity.
Hence the velocity is increased by increasing the potential difference between the anode and filament.