How to Find Strong Reflections Using Bragg's Law?

[freefallin38]

[SOLVED] X-ray reflection/Bragg's law help??

Homework Statement

The planes of atoms in a cubic crystal lie parallel to the surface, 0.81 nm apart. X rays having wavelength 0.37 nm are directed at an angle θ to the surface.

(a) For how many values of θ will there be a strong reflection?
4
(b) What is the largest value of θ that gives a strong reflection?

(c) What is the second largest value of θ that gives a strong reflection?

(d) What energy electrons could give the same result?

Homework Equations

Bragg's Law n$$\lambda$$=2*d*sin$$\Theta$$

The Attempt at a Solution

So I guessed for the answer for part a, I found some things online that had 4 angles, but I have no idea how to find the angles?? Can anyone explain to me what a strong reflection actually is and how to find it?

 

[BigJDubs]

For part b and c, you can use Bragg's Law n\lambda=2*d*sin\Theta to solve for the angles. The largest value of \Theta that gives a strong reflection is equal to arcsin(n\lambda/(2*d)), where n is the order of the reflection (in this case it would be 1). The second largest value of \Theta that gives a strong reflection would be arcsin((n+1)\lambda/(2*d)).For part d, the energy of the electrons would be equal to the energy of the X-rays, which is equal to hc/\lambda, where h is Planck's constant, c is the speed of light, and \lambda is the wavelength of the X-rays.