Chapter 19, Problem 19.5P

(a)

Interpretation Introduction

Interpretation:

Angles that can give $n$ as $-1$, $+1$ and $+2$ have to be calculated.

Concept Introduction:

Principle behind diffraction in reflection grating can be stated with the expression as follows:

  $n\lambda =d\left(\sin \theta +\sin \varphi \right)$

Here,

$d$ denotes repeat distance between closely spaced lines.

$n$ denotes order of diffraction.

$\theta$ denotes angle made by emergent line.

$\varphi$ denotes angle made by incident line.

(b)

Interpretation Introduction

Interpretation:

Reason $n$ cannot take value of $+3$ have to be explained.

Concept Introduction:

Refer to part (a).