A diffraction grating with 4297 lines/cm is illuminated by direct sunlight. The

Question

A diffraction grating with 4297 lines/cm is
illuminated by direct sunlight. The first-order
solar spectrum is spread out on a white screen
hanging on a wall opposite the grating.

a) At what angle does the first-order max-
imum for blue light with a wavelength of 462
nm appear?
Answer in units of degrees

b) At what angle does the first-order maximum for red light with a wavelength of 665
nm appear?
Answer in degrees



2. A helium-neon laser (wavelength 821 nm) is
used to calibrate a diffraction grating.
If the first-order maximum occurs at 29.9 (degrees),
what is the line spacing?
Answer in units of m

Explanation / Answer

(a+b)sin = n , where a+b = 1/(no. of lines per cm)

for first order maxima, n =1

A).. wavelength =  462nm =  462x10-7 cm

(1/4297)sin = 462x10-7

sin = 0.197662

= 11.4 degrees

wavelength = 665x10-7 cm

sin = 4297x  665x10-7 =0.2857505

=16.604 degrees.

sin = line spacingxwavelength

sin(29.9) = line spacing x 821 x10-7

line spacing = 5905 lines per cm

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.