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प्रश्न
What are the conditions for obtaining a good interference pattern? Give reasons.
What is the essential condition for obtaining sustained interference?
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उत्तर १
The conditions necessary for obtaining a well-defined and steady interference pattern are:
- The two sources of light should be coherent: This is the essential condition for getting a sustained interference pattern. As we have seen, the waves emitted by two coherent sources are always in phase or have a constant phase difference between them at all times. If the phases and phase differences vary with time, the positions of maxima and minima will also change with time, and the interference pattern will not be steady. For this reason, it is preferred that the two secondary sources used in the interference experiment are derived from a single original source.
- The light should be monochromatic: As can be seen from the condition of bright and dark fringes, the position of these fringes as well as the width of the fringes depend on the wavelength of light and the fringes of different colours are not coincident. The resultant pattern contains coloured, overlapping bands.
- The two interfering waves must have the same amplitude: Only if the amplitudes are equal, the intensity of dark fringes (destructive interference) is zero and the contrast between bright and dark fringes will be maximum.
- The two light sources should be narrow: If the slits are broad, the distances from different points along the slit to a given point on the screen are significantly different and therefore, the waves coming through the same slit will interfere among themselves, causing blurring of the interference pattern.
- The interfering light waves should be in the same state of polarization: Otherwise, the points where the waves meet in the opposite phase will not be completely dark and the interference pattern will not be distinct.
- The two waves should be in the same state of polarization: This is necessary only if polarized light is used for the experiment.
उत्तर २
- The two light sources must be coherent, which implies that the light waves they emit must have a constant phase difference or be the same phase.
- The two series must emit light of the same wavelength, but the amplitude between them should differ as little as possible.
संबंधित प्रश्न
Four light waves are represented by
(i) \[y = a_1 \sin \omega t\]
(ii) \[y = a_2 \sin \left( \omega t + \epsilon \right)\]
(iii) \[y = a_1 \sin 2\omega t\]
(iv) \[y = a_2 \sin 2\left( \omega t + \epsilon \right).\]
Interference fringes may be observed due to superposition of
(a) (i) and (ii)
(b) (i) and (iii)
(c) (ii) and (iv)
(d) (iii) and (iv)
A long narrow horizontal slit is paced 1 mm above a horizontal plane mirror. The interference between the light coming directly from the slit and that after reflection is seen on a screen 1.0 m away from the slit. If the mirror reflects only 64% of the light energy falling on it, what will be the ratio of the maximum to the minimum intensity in the interference pattern observed on the screen?
In Young’s double slit experiment, the slits are separated by 0.5 mm and screen is placed 1.0 m away from the slit. It is found that the 5th bright fringe is at a distance of 4.13 mm from the 2nd dark fringe. Find the wavelength of light used.
Why are multiple colours observed over a thin film of oil floating on water? Explain with the help of a diagram.
Describe Young's double-slit interference experiment and derive conditions for occurrence of dark and bright fringes on the screen. Define fringe width and derive a formula for it.
What are coherent sources of light?
Explain constructive and destructive interference with the help of a diagram?
What is a bandwidth of interference pattern?
Explain Young’s double-slit experimental setup and obtain the equation for path difference.
Two independent monochromatic sources cannot act as coherent sources, why?
The interference pattern is obtained with two coherent light sources of intensity ratio n. In the interference pattern, the ratio `("I"_"max" - "I"_"min")/("I"_"max" + "I"_"min")` will be ______
The distance between the first and ninth bright fringes formed in a biprism experiment is ______.
(`lambda` = 6000 A, D = 1.0 m, d = 1.2 mm)
In Young's experiment for the interference of light, the separation between the silts is d and the distance of the screen from the slits is D. If D is increased by 0.6% and d is decreased by 0.2%, then for the light of a given wavelength, which one of the following is true?
"The fringe width ____________."
In Young's double slit experiment with a source of light of wavelength 5860 Å, the first maxima will occur when ____________.
In interference experiment, intensity at a point is `(1/4)^"th"` of the maximum intensity. The angular position of this point is at (sin30° = cos60° = 0.5, `lambda` = wavelength of light, d = slit width) ____________.
If the two slits in Young's double slit experiment have width ratio 9 : 1, the ratio of maximum to minimum intensity in the interference pattern is ______.
In the Young's double slit experiment, if the phase difference between the two waves interfering at a point is `phi`, the intensity at that point is proportional to ____________.
In a double slit experiment, the separation between the slits is d and distance of screen from slits is D. If the wavelength of light used is `lambda` and I is the intensity of central bright fringe, then intensity at distance x from central maximum is given by ____________.
Two identical light sources s1 and s2 emit light of same wavelength `lambda`. These light rays will exhibit interference if their ______.
In the biprism experiment, the fringe width is 0.4 mm. What is the distance between the 4th dark band and the 6th bright band on the same side?
The graph shows the variation of fringe width (β) versus distance of the screen from the plane of the slits (D) in Young's double-slit experiment Keeping other parameters the same. The wavelength of light used can be calculated as d = distance between the slits ______
In a biprism experiment, monochromatic light of wavelength (λ) is used. The distance between two coherent sources is kept constant. If the distance between slit and eyepiece (D) is varied as D1, D2, D3, and D4, the corresponding measured fringe widths are z1, z2, z3, and z4 then ______
A double slit experiment is immersed in water of refractive index 1.33. The slit separation is 1 mm, distance between slit and screen is 1.33 m. The slits are illuminated by a light of wavelength 6300 Å. The fringe width is ______.
Two coherent sources of intensities I1 and I2 produce an interference pattern on the screen. The maximum intensity in the interference pattern is ______
What is meant by Constructive interference?
A beam of electrons is used in Young's double-slit experiment. If the speed of electrons is increased then the fringe width will ______.
In biprism experiment, the distance of 20th bright band from the central bright band is 1.2 cm. Without changing the experimental set-up, the distance of 30th bright band from the central bright band will be ______.
