Advertisements
Advertisements
प्रश्न
Explain experimental setup for Fraunhofer diffraction with neat diagram.
उत्तर
- Set up for Fraunhofer diffraction has a monochromatic source of light S at the focus of a converging lens. Ignoring aberrations, the emerging beam will consist of plane parallel rays resulting in-plane wavefronts.
- These are incidents on the diffracting element such as a slit, a circular aperture, a double slit, a grating, etc.
- In the case of a circular aperture, S is a point source and the lenses are bi-convex. For linear elements like slits, grating, etc., the source is linear and the lenses are cylindrical in shape so that the focussed image is also linear.
Set up for Fraunhofer diffraction - An emerging beam is an incident on another converging lens that focuses the beam on a screen.
APPEARS IN
संबंधित प्रश्न
What is the diffraction of light? How does it differ from interference? What are Fraunhofer and Fresnel diffractions?
In a biprism experiment, the fringes are observed in the focal plane of the eyepiece at a distance of 1.2 m from the slits. The distance between the central bright and the 20th bright band is 0.4 cm. When a convex lens is placed between the biprism and the eyepiece, 90 cm from the eyepiece, the distance between the two virtual magnified images is found to be 0.9 cm. Determine the wavelength of light used.
The bending of a beam of light around corners of obstacle is called ______
What should be the slit width to obtain pronounced diffraction with a single slit illuminated by the light of wavelength λ?
What must be the ratio of the slit width to the wavelength for a single slit, to have the first diffraction minimum at 45˚?
Explain Fraunhofer diffraction at a single slit with a neat ray diagram. Obtain an expression for the width of the central bright fringe.
In biprism experiment, the distance between source and eyepiece is 1.2 m, the distance between two virtual sources is 0.84 mm. Then the wavelength of light used if eyepiece is to be moved transversely through a distance of 2.799 cm to shift 30 fringes is ______.
A diffraction is obtained by using a beam of yellow light. What will happen if the yellow light is replaced by the red light?
A slit of width a is illuminated by white light. For red light `(λ = 6500 Å)`, the first minima is obtained at θ = 60°. Then the value of a will be ______.
In a single slit diffraction experiment. fir t minimum for red light (589 nm) coincides with first maximum of some other wavelength `lambda'`. The value of `lambda'` is ______.
In a single slit diffraction pattern, which of the following is incorrect for fringe pattern?
The angular spread of central maximum, in diffraction pattern, does not depend on ______.
A slit of width 'a' illuminated by white light. The first diffraction minimum for light of wavelength 6500 Å is formed at θ = 30°, then 'a' is (sin 30° = 0.5).
In a single slit diffraction experiment, first minimum for a light of wavelength 480 nm coincides with the first maximum of another wavelength `lambda.` Then `lambda'` is ____________.
A plane wavefront of wavelength `lambda`. is incident on a slit of width a. The angular width of principal maximum is ______.
When two coherent sources in Young's experiment are far apart, then interference pattern ______
In Young's double slit experiment, the fringe width is 12 mm. If the entire arrangement is placed in water of refractive index `4/3`, then the fringe width becomes (in mm) ______.
In Young's double experiment, in air interference pattern second minimum is observed exactly in front of one slit. The distance between the two coherent source is 'd' and the distance between source and screen is 'D'. The wavelength of light source used is ______.
In Young's double silt experiment, two slits are d distance apart. The interference pattern is observed on a screen at a distance D from the slits. The first dark fringe is observed on the screen directly opposite to one of the slits. The wavelength of light is ______.
A mixture of light, consisting of wavelength 590 nm and an unknown wavelength, illuminates Young's double slit and gives rise to two overlapping intererence patterns on the screen. The central maximum of both lights coincides.
Further, it is observed that the third bright fringe of known light coincides with the 4th bright fringe of the unknown light. From this data the wavelength of the unknown light is ______.
The angular width of the central maximum of the diffraction pattern in a single slit (of width a) experiment, with λ as the wavelength of light, is ______.
In Young's double slit experiment using monochromatic light of wavelength λ, the maximum intensity of light at a point on the screen is K units. The intensity of light at point where the path difference is `lambda/3` is ______.
`[cos60^circ = sin30^circ 1/2]`
In a biprism experiment, the slit is illuminated by red light of wavelength 6400 A and the crosswire of eyepiece is adjusted to the centre of 3rd bright band. By using blue light it is found that 4th bright band is at the centre of the cross wire. Calculate the wavelength of blue light.
Using the geometry of the double slit experiment, derive the expression for fringe width of interference bands.
