In the Davisson-Germer experiment,an electron beam of energy $60 \ eV$ is incident normally on a crystal surface. If the maximum intensity is observed at an angle of $50^\circ$ with the direction of the incident beam,what is the interatomic spacing in the crystal lattice in $\mathring A$?

What is the uncertainty in the velocity of an electron if the uncertainty in the measurement of its position is $50 \text{ pm}$? $(m_e = 9.1 \times 10^{-31} \text{ kg}, h = 6.63 \times 10^{-34} \text{ Js}, \pi = 3.142)$

In the Davisson-Germer experiment,an electron beam of energy $75 \ eV$ falls normally on the surface of a crystal. If the maximum intensity is obtained at an angle of $45^o$ to the direction of the incident beam,then the inter-atomic distance in the lattice plane of the crystal will be .............. $\mathring{A}$

The wave property of electrons implies that they will show diffraction effects. Davisson and Germer demonstrated this by diffracting electrons from crystals. The law governing the diffraction from a crystal is obtained by requiring that electron waves reflected from the planes of atoms in a crystal interfere constructively (see figure).

Given below are two statements: One is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A:$ The beam of electrons shows wave nature and exhibits interference and diffraction.
Reason $R:$ Davisson-Germer experimentally verified the wave nature of electrons.
In the light of the above statements,choose the most appropriate answer from the options given below:

Which phenomenon best supports the theory that matter has a wave nature?