The angular width of central maxima is given by 2θ=a2λ where, λ = wavelength of light used a= width of the slit For λ1=6000A˚,2θ=θ0 (given) For another light of wavelength λ2 (says), the angular wid th decreases by 30% so, 2θ=(100100−30)θ0=10070θ0=0.7θ0 As slit width is constant, so using Eq. (i) for these values, we get 0.7θ0θ0=λ2λ1⇒λ2=λ1×0.7=6000×0.7=4200A˚
Angular width of the central maxima in the Fraunhoffer diffraction for λ=6000 Å is θ_0. When the same slit is illuminated by another monochromatic…
NEET UG 2019 — Physics Optics
2019mcqeasy
Angular width of the central maxima in the Fraunhoffer diffraction for λ=6000A˚ is θ0. When the same slit is illuminated by another monochromatic light, the angular width decreases by 30%. The wavelength of this light is
Official previous-year question
Held on 30 Apr 2019 · Verified 9 Jul 2026.
Options
- A
1800A˚
- B
4200A˚
- C
6000A˚
- D
420A˚
Did you get this right?
Sign in to track your attempts and accuracy.
Your note
Sign in to keep a private note on this question. Nothing you write is ever public.
NEET UG Optics in other years
More NEET UG Optics questions
Two thin lenses of focal lengths f₁ = +20 cm and f₂ = -10 cm are in contact. The power of the combination is:
2026easy
The refractive index of glass is 1.5. The speed of light in glass is:
2026easy
In a certain camera, a combination of four similar thin convex lenses are arranged axially in contact. Then the power of the combination and the total magnification in comparison to the power $(p)$ and magnification $(m)$ for each lens will be, respectively
2025medium
A microscope has an objective of focal length 2 cm , eyepiece of focal length 4 cm and the tube length of 40 cm . If the distance of distinct vision of eye is 25 cm , the magnification in the microscope is :
2025medium
The intensity of transmitted light when a polaroid sheet, placed between two crossed polaroids at $22.5^{\circ}$ from the polarization axis of one of the polaroid, is ( $\mathrm{I}_0$ is the intensity of polarised light after passing through the first polaroid):
2025medium
Other Physics topics for NEET UG
Keep practicing Optics
Work through every NEET UG Optics PYQ, year by year.