Question

A grating has 6000 lines per cm. How many orders of light of wavelength 4500 A ^0 can be seen

Answer 1

we have to find the number of orders of light of wavelength 4500 A° when a grating has 6000 lines per cm.

solution : number of orders of light of wavelength is given by, n = 1/Nλ

where N = 6000 lines per cm and λ = 4500 A° = 4500 × 10^-8 cm

so, n = 1/(6000 × 4500 × 10^-8)

= 1/(2.7 × 10¯¹)

= 10/2.7

= 3.7 < 4

so number of orders of light is 3.