Advertisements
Advertisements
Question
What is the effect on the interference fringes to a Young’s double slit experiment when
(i) the separation between the two slits is decreased?
(ii) the width of a source slit is increased?
(iii) the monochromatic source is replaced by a source of white light?
Justify your answer in each case.
Advertisements
Solution
(i) From the fringe width expression,
`beta =(lambdaD)/d`
With the decrease in separation between two slits, ‘d’ the fringe width increases.
(ii) For interference fringes to be seen
`s/S<lambda/d,`condition should be satisfied
Where, s = size of the source,
S = distance of the source from the plane of two slits.
As the source slit width increase, fringe pattern gets less and less sharp.
When the source slit is so wide the above condition does not satisfied and the interference pattern disappears.
(iii) The interference pattern due to different colour component of white light overlap. The central bright fringes for different colours are at the same position. Therefore central fringes are white. And on the either side of the central whit fringe coloured bands will appear.
The fringe closed on either side of central white fringe is red and the farthest will be blue. After a few fringes, no clear fringe pattern is seen.
RELATED QUESTIONS
In Young's double slit experiment, using monochromatic light of wavelength λ, the intensity of light at a point on the screen where path difference is λ, is K units. Find out the intensity of light at a point where path difference is `λ/3`.
In Young’s experiment, the ratio of intensity at the maxima and minima in an interference
pattern is 36 : 9. What will be the ratio of the intensities of two interfering waves?
If one of two identical slits producing interference in Young’s experiment is covered with glass, so that the light intensity passing through it is reduced to 50%, find the ratio of the maximum and minimum intensity of the fringe in the interference pattern.
In Young’s double slit experiment, show graphically how the intensity of light varies with distance
How does the fringe width get affected, if the entire experimental apparatus of Young is immersed in water?
A thin transparent sheet is placed in front of a Young's double slit. The fringe-width will _____________ .
In a Young's double slit experiment, two narrow vertical slits placed 0.800 mm apart are illuminated by the same source of yellow light of wavelength 589 nm. How far are the adjacent bright bands in the interference pattern observed on a screen 2.00 m away?
Young's double slit experiment is made in a liquid. The 10th bright fringe lies in liquid where 6th dark fringe lies in vacuum. The refractive index of the liquid is approximately
- Assertion (A): In Young's double slit experiment all fringes are of equal width.
- Reason (R): The fringe width depends upon the wavelength of light (λ) used, the distance of the screen from the plane of slits (D) and slits separation (d).
In Young's double slit experiment, show that:
`β = (λ"D")/"d"`
Where the terms have their usual meaning.
