Chapter 7, Problem 7.19QAP

Interpretation Introduction

(a)

Interpretation:

Reciprocal linear dispersion of a monochromator for first− order spectra is to be determined.

Concept introduction:

Reciprocal linear dispersion gives the relationship between the focal length of the monochromator, the order of monochromator and the distance (d) between slits. An instrument which can resolve every spectra detail, this ability of an instrument is called as linear dispersion and reciprocal of linear dispersion is called reciprocal linear dispersion. The mathematical expression of this relationship can be given as-

$D^{-1}=\frac{d}{nf}$ ...... Eq. (1)

Where,

D-1 = reciprocal linear dispersion

1/d = blazes per millimeter

n= number of the order of monochromator

f= focal length of the monochromator

Interpretation Introduction

(b)

Interpretation:

The first order resolving power of given monochromator is to be determined.

Concept introduction:

Resolving power of monochromator can be calculated by using the following formula:

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

Where,

Δλ = small separation of given wavelength.

λ= wavelength.

And the number of lines for monochromator is calculated by the following condition:

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

Interpretation Introduction

(c)

Interpretation:

The minimum wavelength difference for the theory to be completely resolved by the instrument at 400 nm (approximately) should be determined.

Concept introduction:

Resolving power of the instrument will be used. The formula of resolving power is given as:

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