Question

Bragg gave a mathematical equation:

$n\lambda =2dsin\theta$

Here which of the following is correct?

• A. $\lambda \to$ wavelength of incident x-ray
• B. d $\to$ distance between the layers
• C.
• D. ɵ →

Answer 1

Answer: (A), (B), (D)

The correct options are
A

$\lambda \to$ wavelength of incident x-ray

B

d $\to$ distance between the layers

D

ɵ →

Recall the experiment which you saw in the videos.

We got the formula as,

n $\lambda$ = 2d sin$\theta$

How we came to this conclusion,

For peaks, we know that we need the following arrangement:

and this will be repeated for integral multiple of $\lambda$.

Therefore, n $\to$ an integer

$\lambda \to$ wavelength of x-ray

Now, look at the crystal diagram.

Here you can see that,

d$\to$ distance between the layers.

$\theta \to$ angle between incident x-rays and the plane of crystal.

Therefore, (a), (b) and (d) are correct.

Do not get confused in e, it is not angle between the incident x-ray and the perpendicular of the plane.