Home
Class 12
PHYSICS
A thin plastic of refractive index 1.6 i...

A thin plastic of refractive index 1.6 is used to cover one of the slits of a double slit arrangement. The central point omn the screen is now occupied by what would have been the 7th bright fringe before the plastic was used. If the wavelength of light is 600 nm, what is the thickness ( in `mu`m ) of the plastic?

A

7

B

4

C

8

D

6

Text Solution

Verified by Experts

The correct Answer is:
A
Here, `mu=1.6,n=7,lamda=600nm,t=?`
According to question, shift in central point due to insertion of plastic sheet=`7beta`
or `((mu-1)tD)/(d)=7xx(Dlamda)/(d)`
`therefore t=(7lamda)/(mu-1)=(7xx600xx10^(-9))/(1.6-1)=(7xx6xx10^(-7))/(0.6)=7xx10^(-6)m`
`implies t=7mum`.
Promotional Banner

Topper's Solved these Questions

  • WAVE OPTICS

    MTG-WBJEE|Exercise WB JEE PREVIOUS YEARS QUESTION (MCQ.s)|9 Videos

  • THERMODYNAMICS

    MTG-WBJEE|Exercise WB JEE Previous Years Questions|12 Videos

  • WORK, POWER, ENERGY

    MTG-WBJEE|Exercise EXERCISE (WB JEE Previous Years Questions) CATEGORY 1 : Single Option Correct Type (1 Mark)|3 Videos

Similar Questions

Explore conceptually related problems

A thin sheet of glass (refractive index 1.5) of thickness 6 microns, introduced in the path of one of the interfering beams in a double-slit experiment shift the central fringe to a position earlier occupied by the fifth bright fringe. The wavelength of light used is

A very thin sheet of plastic having refractive index mu=1.5 covers one slit of a double slit apparatus illuminated by 700 nm light . The central point on the screen , instead of being maximum , is dark . What is the possible thickness of the plastic in (nm) ?

One slit of a double slits experiment is covered by a thin glass plate of refractive index 1.4 and the other by a thin glass plate of refractive index 1.7 .The point on the screen ,where central bright fringe was formed before the introduction of the glass sheets,is now occupied by the 15th bright fringe.Assuming that both the glass plates have same thickness and wavelength of light used in 4800Å ,find the their thickness.

When the plastic thin film of refractive index 1.45 is placed in the path of one of the interfering waves then the central fringe is displaced through width of five fringes.The thickness of the film will be ,if the wavelength of light is 5890Å

In a double-slit experiment, fringes are produced using light of wavelength 4800A^(@) . One slit is covered by a thin plate of glass of refractive index 1.4 and the other slit by another plate of glass of double thickness and of refractive index 1.7. On doing so, the central bright fringe shifts to a position originally occupied by the fifth bright fringe from the centre. find the thickness of the glass plates.

In Young's double slit experiment a mica plate of refractive index mu is introduced in the path of light coming from one of the slit . If the central bright frige gets shifted to the point originally occupied by the fourth bright fringe, then the thickness of the mica plate will be ( symbols have their usual meaning )

With two slits spaced 0.2 mm apart and a screen at a distance of 1 m, the third bright fringe is found to be at 7.5 mm from the central fringe. The wavelength of light used is

In Young's double-slit experiment the angular width of a fringe formed on a distant screen is 1^(@) . The wavelength of light used is 6000 Å . What is the spacing between the slits?