Answer:
the number of lines is 526
Explanation:
The wavelength λ =600nm = 600 × 10⁻⁶ mm
The diffraction angle θ = 39°
Recall the expression for the relation between the wavelength, angle and central maxima distance.
Recall the expression for the relation between the wavelength, angle and central maxima distance.
Recall the expression for the relation between the wavelength, angle and central maxima distance.
relation between the wave length, angle and central maxima distance
d = nλ / sinθ
Here n = 2 for second order maxima and d is the distance
= 2(600 × 10⁻⁶) / sin 39°
= 1200 × 10⁻⁶ / 0.6293
= 1.9 × 10⁻³ mm
N = 1/d
= 1 / 1.9 × 10⁻³
= 526
The grating has a line density of 526 lines per millimeter
