Chapter 7, Problem 7.18QAP

Interpretation Introduction

(a)

Interpretation:

The focal length value of a monochromator is 1.6 cm. This monochromator also has collimating mirror whose diameter value is 3.5 cm and this dispersion device is grating with the value of 1500 line/mm. Resolving power of this monochromatic device is to be determined for first order grating, at the condition that the illumination of the collimated beam occurs at 3.2 cm of the grating.

Concept introduction:

Resolving power of monochromatic device is calculated by using the following formula:

$R=\frac{\lambda }{\Delta \lambda }=nN$

Distance between slit and the no. of lines also given as:

$d=\frac{1}{N}$

Interpretation Introduction

(b)

Interpretation:

First and second order reciprocal linear dispersion of a monochromator with focal length 1.6 cm is to be determined.

Concept introduction:

Formula for reciprocal linear dispersion is given as:

$D^{-1}=\frac{d}{nf}$    ......(1)

Here,

D-1= reciprocal linear dispersion

1/d= no. of lines/ mm

n= no. of order

f= focal length