Wave property of electron implies that they will show diffraction effected . Davisson and Germer demonstrated this by diffracting electron from crystals . The law governing the diffraction from a crystals is obtained by requiring that electron waves reflected from the planes of atoms in a crystal inter fere constructiely

If a strong diffraction peak is observed when electrons are incident at an angle `i` from the normal to the crystal planes with distance `d` between them (see fig) de Brogle wavelength `lambda_(dB)` of electrons can be calculated by the relationship (n is an intenger)

Options

A. `30^(@)`
B. `15^(@)`
C. `45^(@)`
D. `60^(@)`

Explanation

Glancing angle is the inclination of the incident rays with the plane of the atoms which is,
`theta=90^(@)-30^(@)=60^(@)`