- #1

steve233

- 20

- 0

## Homework Statement

We have access to X-ray and electrons for the incident beam.

[itex] \theta [/itex] is the inner angle between the sample and the incident beam.

Spacing in sample = d =10^-10 m

[itex] \lambda [/itex] = 10^-10 m

a) What values of [itex] \theta [/itex] will we measure X-rays at a detector, that is, when will there be constructive interference (assume elastic collision)?

b) If we use electrons instead of X-rays, at which energy should they be to detect the electrons at the same angle as the X-rays (assume elastic collision)?

## Homework Equations

Bragg's Law:

[itex]2 d sin(\theta) = m \lambda[/itex]

E = hf

p = h / [itex] \lambda [/itex]

Compton effect

## The Attempt at a Solution

For part (a) what I did was basically use:

[itex]sin(\theta) = (1 \lambda) / (2d)[/itex]

[itex]sin(\theta) = (2 \lambda) / (2d)[/itex]

Since [itex]sin(\theta) = (2 \lambda) / (2d)[/itex] gives 90 degrees, my answer is that the only angle is 30 degrees, that is, m = 1.

For part (b) I'm not really sure how to approach this question. Is this just the classical model of an elastic collision?

Thanks.