When monochromatic light illuminates a grating with 7000 lines per centimeter, its second order maximum is at 62.4°. What is the wavelength of the lig

633nm

Explanation:

Given the following :

Number of lines per centimeter(N) = 7000

Angle θ = 62.4°

Order (n) = 2

If grating element = d

Wavelength (λ) = (d* SinΘ) / 2

If number of lines = 7000 per cm

Converting to metre :

100 cm = 1m

7000 lines per 1 cm

Number of lines per m:

7000 lines * 100 = 700,000 lines per meter

Recall :

d = reciprocal of N

d = 1 / 700,000

d = 0.00000142857

Substituting into (λ) = (d* SinΘ) / 2

λ = (0.00000142857 * Sin 62.4°) / 2

λ = 0.00000126600 / 2

λ = 0.000000633002

λ = 0.000000633

λ = 633 × 10^-9 m = 633nm

nah.   i'm just sleepy.