When one of the slits of Young's experiment is covered with a transparent sheet of thickness 4.8 mm, the central fringe shifts to a position originally occupied by the 30th bright fringe. What should be the thickness of the sheet if the central fringe has to shift to the position occupied by the 20th bright fringe?
Correct answer: D. 3.2 mm
- A. 3.8 mm
- B. 1.6 mm
- C. 7.6 mm
- D. 3.2 mm
Explanation
When one of the slits is covered with a sheet of thickness 4.8 mm, the central fringe shifts to the position of the 30th bright fringe. To shift it to the 20th bright fringe, the sheet thickness needs to be reduced. The correct thickness of the sheet to achieve this shift is 3.2 mm. The other options do not align with the required shift in the central fringe position.
Report an error
The more specific you are, the faster it gets fixed. A source beats an opinion.
Prefer email? [email protected]
About Optics
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.
Practise Optics
665 free Optics MCQs from Physics, each with the correct answer and an explanation. Unlimited attempts, no account needed.
Discussion
Stuck on an option, or know a faster way to get there? Ask or explain it here.
No comments yet. Be the first to explain this one.
Exams that ask Physics questions like this
Physics is on 11 papers prepared for on TestUstad, and all of them draw the same bank, so this question is worth knowing for every one of them.
More Optics questions
Plane polarised light is passed through a polaroid. On viewing through the polaroid, we find that when the polaroid is given one complete rotation about the direction of the light, one of the following is observed :
The figure shows a double-slit experiment. P and Q are the slits. The path lengths PX and QX are nλ and (n+2)λ respectively, where n is a whole number and λ is the wavelength. Taking the central fringe as zero, what is formed at X:
Light of wavelength λ is incident on a slit. The first minima of the diffraction pattern is found to lie at a distance of 6 mm from the central maximum on a screen placed at a distance of 2 m from the slit. If the slit width is 0.2 mm, then the wavelength of the light used will be:
The periodic time of rotation of a certain star is 22 days and its radius is 7 x 10^8 metres. If the wavelength of light emitted by its surface is 4320 Å, the Doppler shift will be: (1 day = 86400 sec)
In a two-slit experiment with monochromatic light, fringes are obtained on a screen placed at some distance from the slits. If the screen is moved by 5 x 10^-2m towards the slits, the change in fringe width is 3 x 10^-5 m. If the separation between the slits is 10-3 m, the wavelength of light used is:
In a YDSE the separation between the slits is 1 mm and the screen is at a distance of 2 m from the plane of the slits. The wavelength missing on the screen at a point directly in front of one of the slits is: