Red light of wavelength 625 nm is incident normally on an optical diffraction grating with $\ 2 imes 10^{5}$ lines/m. Including central principal maxima, how many maxima may be observed on a screen which is for from the grating?

Question

Red light of wavelength 625 nm is incident normally on an optical diffraction grating with $\ 2 	imes 10^{5}$ lines/m. Including central principal maxima, how many maxima may be observed on a screen which is for from the grating?

Dr. Abubacker · Accepted Answer

(b) For principal maxima in grating spectra
$\frac{\sin	heta}{N} = n\lambda$
Where, $n = (1,\ 2,\ 3)$ is the order of principal maxima and $	heta$ is the angle of diffraction.
$n = \frac{1}{\lambda N} = \frac{1}{6.25 	imes 10^{- 7} 	imes 2 	imes 10^{5}} = 8$
$	herefore$ Number of maxima $= 2n + 1 = 2 	imes 8 + 1 = 17$

Q. Red light of wavelength 625 nm is incident normally on an optical diffraction grating with $\ 2 \times 10^{5}$ lines/m. Including central principal maxima, how many maxima may be observed on a screen which is for from the grating?

Explanation

Reviewed by Dr. Abubacker

Want more practice?