Crystal diffraction experiments can be performed using X-rays, or electrons accelerated through appropriate voltage. Which probe has greater energy? An X-ray photon or the electron? (For quantitative comparison, take the wavelength of the probe equal to `1Å`, which is of the order of interatomic spacing in the lattice), `m_(e)=9.11xx10^(-31)kg`.

Explanation

Given `lambda = 1 A = 10^(-10) m, m_(e) = 9.11 xx10^(-31) ` kg, h `= 6.63 xx10^(-34) ` j - s , c = ` 3 xx 10^(8)` m/s
` lambda = h/(sqrt(2"mKE")) rArr KE - (h^(2))/(2mlambda^(2)) = ((6.63 xx10^(-34))^(2))/(2 xx 9.11 xx10^(-31) xx(10^(-10))^(2))eV =150.78 eV`
`E=(hc)/(lambda)=(6.63xx10^(-34)xx3xx10^(8))/(10^(-10)xx1.6xx10^(-19))eV=12.4xx10^(3)eV`
Thus, for the wavelength a X - ray photon has much KE than an electron .