Single correct · +4 / −1
The Davisson-Germer experiment demonstrated:
- (a) existence of the electron
- (b) wave nature of electrons
- (c) quantization of charge
- (d) photoelectric effect
Answer and solution
Answer (b) wave nature of electrons
Solution
Physics sir · 4 steps
Electrons scattered off a crystal gave a diffraction peak, and only waves diffract.
- The setup. A beam of electrons, accelerated through 54 V, was fired at a nickel crystal. The number of electrons scattered at each angle was measured.
- What they saw. The scattered intensity showed a sharp peak at about 50°. The regular rows of atoms in the crystal act like a grating, and a peak like this is a diffraction pattern.
- Check with de Broglie. The wavelength worked out from the diffraction was about 0.165 nm. De Broglie's λ = h/p = 1.227/√V nm = 1.227/√54 nm ≈ 0.167 nm matches it closely.
- So. Diffraction is a wave property, so the experiment showed that electrons behave as waves. This confirmed de Broglie's hypothesis, which is option (b).
The idea to keep. Any diffraction or interference pattern is proof of wave behaviour. Davisson-Germer is the matter-wave proof: electrons diffracted by a crystal, matching λ = h/p.
Answer from the NTA final answer key. Solution by PrepWiser.