Find the minimum number of lines required in a grating of width 2 cm so that the two Na lines of 5890 & 5896 $\mathring{A}$ are just resolved in the 1st order spectra.

6.2kviews

written 7.9 years ago by

neeta.vanage • 880

modified 3.9 years ago by

pedsangini276 • 4.8k

Subject: Applied Physics 2

Topic: Interference And Diffraction

Difficulty: Medium

engineering physics

ADD COMMENT EDIT

1 Answer

1.6kviews

written 7.8 years ago by

neeta.vanage • 880

modified 7.8 years ago by

mananbothra • 100

RP = $\frac{\lambda}{d\lambda}$ = nN

$λ = \frac{5890+5896}{2} = 5893 A° $

dλ = 5896-5890 = 6 A°

$\frac{λ}{dλ}$ = 982

982 = 1 x N

Therefore N=982 lines /cm

For grating of width 2 cm N = 982 x2 = 1964

Create a free account to keep reading this post.

and 4 others joined a min ago.

ADD COMMENT EDIT

Please log in to add an answer.