Question

If a strong diffraction peak is observed when electrons are incident at and angle $i$ from the normal to the crystal planes with distances $d$ between them (see figure), de-Broglie wavelength ${\lambda }_{dB}$ of electrons can be calculate by the relationship (n is an integer)

• A. $d\sin i=n{\lambda }_{dB}$
• B. $2d\cos i=n{\lambda }_{dB}$
• C. $2d\sin i=n{\lambda }_{dB}$
• D. $d\cos i=n{\lambda }_{dB}$

Answer 1

The correct option is B $2d\cos i=n{\lambda }_{dB}$

$2dsin\theta ={n\lambda }_{db}$

$2dsin(90-i)={n\lambda }_{db}$

$2d\left(cosi\right)={n\lambda }_{db}$