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Light emitted by element X passes through a diffraction grating that has 1200 slits/mm. The interference pattern is observed on a screen 77.
Question
Light emitted by element X passes through a diffraction grating that has 1200 slits/mm. The interference pattern is observed on a screen 77.0 cm behind the grating. First-order maxima are observed at distances of 58.0 cm , 65.4 cm , and 94.5 cm from the central maximum. What are the wavelengths of light emitted by element X?
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4 years
2021-08-13T07:13:06+00:00
2021-08-13T07:13:06+00:00 1 Answers
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Answers ( )
Answer:
500 nm, 530 nm, 650 nm
Explanation:
Let’s say that there is diffraction grating observed with a slit spacing of s. Respectively we must determine the angle θ which will help us determine the 3 wavelengths ( λ ) of the light emitted by element X. This can be done applying the following formulas,
s( sin θ ) = m
λ, such that y = L( tan θ ) – where y = positioning, or the distance of the first – order maxima, and L = constant, of 77 cm
Now the grating has a slit spacing of –
s = 1 / N = 1 / 1200 = 0.833
10⁻³ mm
The diffraction angles of the ” positionings ” should thus be –
θ = tan⁻¹
( 0.58 / 0.77 ) = 37°,
θ = tan⁻¹
( 0.654 / 0.77 ) = 40°,
θ = tan⁻¹
( 0.945 / 0.77 ) = 51°
The wavelengths of these three bright fringes should thus be calculated through the formula : λ = s( sin θ ) –
λ = 0.833
10⁻³
sin( 37° ) = ( 500
10⁻⁹ m )
λ = 0.833
10⁻³
sin( 40° ) = ( 530
10⁻⁹ m )
λ = 0.833
10⁻³
sin( 51° ) = ( 650
10⁻⁹ m )
Wavelengths : 500 nm, 530 nm, 650 nm