The wavelength of light which produces second order spectrum on diffraction grating on which 5000 lines/cm are ruled at an angle of 30° will be:
Correct answer: C. 5 x 10^-7 m
- A. 6 x 10^-7 m
- B. 4 x 10^-6 m
- C. 5 x 10^-7 m
- D. 3 x 10^-6 m
Explanation
We know, for diffraction grating: dsin𝜭=m𝞴 Where d is the reciprocal of lines per centimeter. Also convert cm into m For second order spectrum m=2 𝞴=dsin𝜭/m =0.01/5000xsin30÷2 =5x10-⁷m Therefore option C is right.
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Light is studied through reflection, refraction, dispersion, interference, diffraction and polarization, linking ray behavior with its wave nature. Questions may involve mirrors, lenses, optical instruments, refractive index and image formation, while geometrical optics deals with rays and wave optics explains effects such as interference and diffraction.
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