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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 the diffraction pattern due to a single slit of width 'd' with incident light of wavelength 'λ', at an angle of diffraction θ. the condition for first minimum is ....
(a)`lambda sin theta =d`
(b) `d costheta =lambda`
(c)`d sintheta=lambda`
(d) `lambda cos theta=d`
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.
Explain why the maxima at `theta=(n+1/2)lambda/a` become weaker and weaker with increasing n
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.
Two wavelengths of sodium light of 590 nm and 596 nm are used in turn to study the diffraction taking place at a single slit of aperture 2 × 10−6 m. The distance between the slit and the screen is 1·5 m. Calculate the separation between the positions of first maxima of the diffraction pattern obtained in the two cases.
In Fraunhofer diffraction, how is the angular width of the central bright fringe affected when slit separation is increased?
Show graphically the intensity distribution in Fraunhofer's single slit diffraction experiment. Label the axes.
Draw the intensity distribution for the diffraction bands produced due to single slit ?
In Fraunhofer diffraction, what kind of a source of light is used and where is it situated?
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 magnifying power of a telescope in normal adjustment is 24, when the length of the telescope tube 1 meter. The focal length of the eye lens is
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):
Which of the following device is used to study the spectra of light?
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.
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.
Derive the expression for the angular position of (i) bright and (ii) dark fringes produced in a single slit diffraction.
In a diffraction pattern due to a single slit, how will the angular width of the central maximum change, if orange light is used in place of green light?
Justify your answer.
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 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 ______.
Draw a labelled graph showing the variation in intensity of diffracted light with diffracting angle in a single slit Fraunhofer diffraction experiment.
