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प्रश्न
Explain two types of diffraction of light.
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उत्तर
The diffraction phenomenon is classified into two types:
1. Fraunhofer diffraction: The source of light and the screen on which the diffraction pattern is obtained are effectively at infinite distance from the diffracting system. In this case, we consider plane wavefront. The diffraction pattern is obtained by using a convex lens.
2. Fresnel diffraction: The source of light and the screen are kept at finite distance from the diffracting system. In this case, we consider a cylindrical or spherical wavefront.
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संबंधित प्रश्न
What is 'diffraction of light'
In a single slit diffraction pattern, the distance between first minima on the right and first minima on the left of central maximum is 4 mm. The screen on which the pattern is displaced, is 2m from the slit and wavelength of light used is 6000Å. Calculate width of the slit and width of the central maximum.
A point is situated at 7cm and 7·2 cm from two coherent sources. Find the· nature of illumination at the point if wavelength of light is 4000A.
For a single slit of width "a", the first minimum of the interference pattern of a monochromatic light of wavelength λ occurs at an angle of λa. At the same angle of λa, we get a maximum for two narrow slits separated by a distance "a". Explain.
Describe briefly how a diffraction pattern is obtained on a screen due to a single narrow slit illuminated by a monochromatic source of light. Hence obtain the conditions for the angular width of secondary maxima and secondary minima.
Draw the intensity distribution for the diffraction bands produced due to single slit ?
Two wavelengths of sodium light 590 nm and 596 nm are used, in turn to study the diffraction taking place at a single slit of aperture 2 × 10−4m. The distance between the slit and the screen is 1.5 m. Calculate the separation between the positions of the first maxima of the diffraction pattern obtained in the two cases.
Two wavelengths of sodium light 590 nm and 596 nm are used, in turn, to study the diffraction taking place due to a single slit of aperture 1 × 10−4 m. The distance between the slit and the screen is 1.8 m. Calculate the separation between the positions of the first maxima of the diffraction pattern obtained in the two cases.
Monochromatic light of wavelength 4300 Å falls on a slit of width ‘a’. For what value of ‘a’ the first maximum falls at 30° ?
In a single slit diffraction experiment, how does the angular width of the central maxima change when:
- screen is moved away from the plane of the slit?
- width of the slit is increased?
- light of larger wavelength is used?
The penetration of light into the region of geomaterial shadow is called.
Diffraction effects are easy to notice in the case of sound waves than in case of light waves because
Direction of the first secondary maximum in the Fraunhoffer diffraction pattern at a single slit is given by (a is the width of the slit):
Consider the diffraction pattern for a small pinhole. As the size of the hole is increased ______.
- the size decreases.
- the intensity increases.
- the size increases.
- the intensity decreases.
A polariod (I) is placed in front of a monochromatic source. Another polatiod (II) is placed in front of this polaroid (I) and rotated till no light passes. A third polaroid (III) is now placed in between (I) and (II). In this case, will light emerge from (II). Explain.
AC = CO = D, S1C = S2C = d << D
A small transparent slab containing material of µ = 1.5 is placed along AS2 (Figure). What will be the distance from O of the principal maxima and of the first minima on either side of the principal maxima obtained in the absence of the glass slab?
Four identical monochromatic sources A, B, C, D as shown in the (Figure) produce waves of the same wavelength λ and are coherent. Two receiver R1 and R2 are at great but equal distances from B.
- Which of the two receivers picks up the larger signal?
- Which of the two receivers picks up the larger signal when B is turned off?
- Which of the two receivers picks up the larger signal when D is turned off?
- Which of the two receivers can distinguish which of the sources B or D has been turned off?
Draw the graph showing intensity distribution of fringes with phase angle due to diffraction through a single slit. What is the width of the central maximum in comparison to that of a secondary maximum?
Write two points of difference between an interference pattern and a diffraction pattern.
In a diffraction pattern due to a single slit, how will the angular width of the central maximum change, if the screen is moved closer to the slit?
Justify your answer.
In a diffraction pattern due to a single slit, how will the angular width of the central maximum change, if the slit width is decreased?
Justify your answer.
In the diagram shown, the separation between the slit is equal to 3λ, where λ is the wavelength of the light incident on the plane of the slits. A thin film of thickness 3λ and refractive index 2 has been placed in the front of the upper slit. The distance of the central maxima on the screen from O is ______.
In a single slit Fraunhofer diffraction experiment, how does the angular width of the central maximum change when the slit width is Increased?
