Q.Describe briefly Davisson – Germer experiment which demonstrated the wave nature of electrons.

Step 1. The apparatus heats a filament with a low-tension battery to emit electrons by thermionic emission; a high-tension battery then accelerates these electrons through a known potential, and two thin aluminium diaphragms collimate them into a narrow beam directed at a single nickel crystal.

Step 2. Because a crystal's regularly spaced atomic planes can act as a natural three-dimensional diffraction grating for waves of comparable wavelength, and an electron's de Broglie wavelength at typical accelerating voltages is of the right order ($10^{-10}$ m), any genuine wave character in the beam should produce a diffraction pattern.

Step 3. A rotatable electron detector measures the scattered beam's intensity as a function of the scattering angle $\theta$; at an accelerating voltage of 54 V, the intensity shows a sharp peak at $\theta=50°$, the signature of constructive interference between electron waves diffracted from successive atomic layers.

Step 4. Using nickel's known interplanar spacing, this peak corresponds to an experimentally measured electron wavelength of 1.65 Å. …

Describe the apparatus, the angle-dependent scattered-intensity measurement, and compare the experimentally deduced wa …

• Omitting the quantitative comparison between the experimental (1.65 A) and theoretical (1.67 A) wavele …