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प्रश्न
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.
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उत्तर
(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.
संबंधित प्रश्न
(i) In Young's double-slit experiment, deduce the condition for (a) constructive and (b) destructive interferences at a point on the screen. Draw a graph showing variation of intensity in the interference pattern against position 'x' on the screen.
(b) Compare the interference pattern observed in Young's double-slit experiment with single-slit diffraction pattern, pointing out three distinguishing features.
Using analytical method for interference bands, obtain an expression for path difference between two light waves.
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 Young's double slit experiment is performed with white light.
(a) The central fringe will be white.
(b) There will not be a completely dark fringe.
(c) The fringe next to the central will be red.
(d) The fringe next to the central will be violet.
A parallel beam of monochromatic light is used in a Young's double slit experiment. The slits are separated by a distance d and the screen is placed parallel to the plane of the slits. Slow that if the incident beam makes an angle \[\theta = \sin^{- 1} \left( \frac{\lambda}{2d} \right)\] with the normal to the plane of the slits, there will be a dark fringe at the centre P0 of the pattern.
What should be the path difference between two waves reaching a point for obtaining constructive interference in Young’s Double Slit experiment ?
A thin circular ring of mass M and radius R is rotating about its axis with a constant angular velocity ω. Two objects each of mass m are attached gently to the opposite ends of diameter of the ring. The ring will now rotate with an angular velocity:
ASSERTION (A): In an interference pattern observed in Young's double slit experiment, if the separation (d) between coherent sources as well as the distance (D) of the screen from the coherent sources both are reduced to 1/3rd, then new fringe width remains the same.
REASON (R): Fringe width is proportional to (d/D).
In Young’s double slit experiment, how is interference pattern affected when the following changes are made:
- Slits are brought closer to each other.
- Screen is moved away from the slits.
- Red coloured light is replaced with blue coloured light.
