Answer:
The wavelength of x-ray is 0.272 nm.
Explanation:
Inter planer spacing, d = 0.399 nm = 3.99 × 10⁻¹⁰ m
First order constructive interference occurs when the beam makes an angle of 20° with the planes. We need to find the wavelength of the x-rays. The condition for constructive interference is given by :
[tex]n\lambda=2d\ sin\theta[/tex]
Here, n = 1
[tex]\lambda=2\times 3.99\times 10^{-10} m\ sin(20)[/tex]
[tex]\lambda=2.72\times 10^{-10}\ m[/tex]
[tex]\lambda=0.272\ nm[/tex]
So, the wavelength of the x-rays is 0.272 nm. Hence, this is the required solution.
