A diffraction grating is illuminated simultaneously with red light of wavelength 670 nm and light of an unknown wavelength. The fifth-order maximum of the unknown wavelength exactly overlaps the third-order maximum of the red light.

What is the unknown wavelength? (in nm)

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24 October, 13:13

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Juliana Owens · Answer 1

dsin∅ = m * λ

so, dsin∅red = 3 (670nm)

also, dsin∅? = 5λ?

however, if they overlap then dsin∅red = dsin∅?

3 (670nm) / 5 = 402nm

∴λ = 402nm

A diffraction grating is illuminated simultaneously with red light of wavelength 670 nm and light of an unknown wavelength. The fifth-order maximum of the unknown wavelength exactly overlaps the third-order maximum of the red light.What is the unknown wavelength? (in nm)