Advertisements
Advertisements
प्रश्न
What are the two methods for obtaining coherent sources in the laboratory?
उत्तर
In the laboratory, coherent sources can be obtained by using (1) Lloyd's mirror and (2) Fresnel's biprism.
- Lloyd's mirror:
This is an extensively used device. The light from a source is made to fall at a grazing angle on a plane mirror as shown in figure.
Some of the light falls directly on the screen as shown by the blue lines in the figure and some light falls after reflection, as shown by the red lines. The reflected light appears to come from a virtual source and so we get two sources. They are derived from a single source and hence are coherent. They interfere and an interference pattern is obtained as shown in the figure. Note that even though we have shown the direct and reflected rays by blue and red lines, the light is monochromatic having a single wavelength. - Fresnel's biprism:
A biprism is a prism with a vertex angle of nearly 180°. It can be considered to be made up of two prisms with very small refracting angle ranging from 30′ to 1°, joined at their bases. In experimental arrangement, the refracting edge of the biprism is kept parallel to the length of the slit. Monochromatic light from a source is made to pass through a narrow slit S as shown in Figure and fall on the biprism.
The two halves of the biprism form virtual images S1 and S2. These are coherent sources having obtained from a single secondary source S. The two waves coming from S1 and S2 interfere and form interference fringes like that in Young’s double-slit experiment in the shaded region shown in the figure.
APPEARS IN
संबंधित प्रश्न
Write the necessary conditions to obtain sustained interference fringes.
When a drop of oil is spread on a water surface, it displays beautiful colours in daylight because of ______________ .
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.
A double-slit arrangement produces interference fringes for sodium light (λ = 589 nm) that are 0.20° apart. What is the angular fringe separation if the entire arrangement is immersed in water (n = 1.33)?
Why two light sources must be of equal intensity to obtain a well-defined interference pattern?
What is interference?
What are coherent sources of light?
Explain constructive and destructive interference with the help of a diagram?
What is phase of a wave?
Obtain the equation for resultant intensity due to interference of light.
A metal rod has length, cross-sectional area and Young's modulus as L, A and Y, respectively. If the elongation in the rod produced is l, then work done is proportional to ______.
On a rainy day, a small oil film on water shows brilliant colours. This is due to ____________.
Two identical light waves having phase difference 'Φ' propagate in same direction. When they superpose, the intensity of the resultant wave is proportional to ______.
In a Young's experiment, two coherent sources are placed 0.60 mm apart and the fringes are observed one metre away. If it produces the second dark fringe at a distance of 1 mm from the central fringe, the wavelength of monochromatic light used would be ____________.
In Young's double-slit experiment, an interference pattern is obtained on a screen by a light of wavelength 4000 Å, coming from the coherent sources S1 and S2 At certain point P on the screen, third dark fringe is formed. Then the path difference S1P - S2P in microns is ______.
In Young's double slit experiment the source is white light. One slit is covered with red filter and the other with blue filter. There shall be ____________.
Two sources of light 0.5 mm apart are placed at a distance of 2.4 m and wavelength of light is 5000 Å. The phase difference between the two light waves interfering on the screen at a point at a distance 3 mm from central bright band is ____________.
In biprism experiment, the 4th dark band is formed opposite to one of the slits. The wavelength of light used is ______.
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 ____________.
`phi "and" phi_2 (phi_1 > phi_2)` are the work functions of metals A and B. When light of same wavelength is incident on A and B, the fastest emitted electrons from A are ____________ those emitted from B.
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 ______
In the biprism experiment, a source of monochromatic light is used for a certain distance between slit and eyepiece. When the distance between two virtual sources is changed from dA to dB, then the fringe width is changed from ZA to ZB. The ratio ZA to ZB is ______
Light waves from two coherent sources arrive at two points on a screen with a path difference of zero and λ/2. The ratio of the intensities at the points is ______
In Young's double-slit experiment, the distance between the slits is 3 mm and the slits are 2 m away from the screen. Two interference patterns can be obtained on the screen due to light of wavelength 480 nm and 600 run respectively. The separation on the screen between the 5th order bright fringes on the two interference patterns is ______
What is meant by Constructive interference?
Show graphically the intensity distribution in a single slit diffraction pattern.
White light is passed through a double slit and interference is observed on a screen 1.5 m away. The separation between the slits is 0.3 mm. The first violet and red fringes are formed 2.0 mm and 3.5 mm away from the central white fringes. The difference in wavelengths of red and violet light is ______ nm.
Two coherent sources P and Q produce interference at point A on the screen where there is a dark band which is formed between 4th bright band and 5th bright band. Wavelength of light used is 6000 Å. The path difference between PA and QA is ______.
