Write the Important Characteristic Features by Which the Interference Can Be Distinguished from the Observed Diffraction Pattern. - Physics


Write the important characteristic features by which the interference can be distinguished from the observed diffraction pattern.



Important characteristic features:

1. Interference is the result of the interaction of light coming from two different waves originating from two coherent sources, whereas the diffraction pattern is the result of the interaction of light coming from different parts of the same wavefront.

2. The fringes may or may not be of the same width in case of interference, while the fringes are always of varying width in diffraction.

3. In interference, the fringes of minimum intensity are perfectly dark and all bright fringes are of the same intensity. In diffraction, the fringes of minimum intensity are not perfectly dark and the bright fringes are of varying intensity.

4. There is a good contrast between the bright and dark fringes in the interference pattern. The contrast between the bright and dark fringes in the diffraction pattern is comparatively poor.

Concept: Interference
  Is there an error in this question or solution?
2014-2015 (March) Panchkula Set 3

Video TutorialsVIEW ALL [1]


Write the necessary conditions to obtain sustained interference fringes.

State any one difference between interference of light and diffraction of light

Laser light of wavelength 630 nm is incident on a pair of slits which are separated by 1.8 mm. If the screen is kept 80 cm away from the two slits, calculate:

1) fringe separation i.e. fringe width.

2) distance of 10th bright fringe from the centre of the interference pattern

How does the angular separation between fringes in single-slit diffraction experiment change when the distance of separation between the slit screens is doubled?

When a drop of oil is spread on a water surface, it displays beautiful colours in daylight because of ______________ .

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 narrow slit S transmitting light of wavelength λ is placed a distance d above a large plane mirror, as shown in the following figure. The light coming directly from the slit and that coming after the reflection interfere at a screen ∑ placed at a distance D from the slit. (a) What will be the intensity at a point just above the mirror, i.e. just above O? (b) At what distance from O does the first maximum occur?

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. Find the fringe-width if the light used has a wavelength of 700 nm.

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?

The intensity at the central maximum (O) in a Young’s double slit experimental set-up shown in the figure is IO. If the distance OP equals one-third of the fringe width of the pattern, show that the intensity at point P, would equal `(I_0)/4`.

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.  

Answer the following question.
Describe any two characteristic features which distinguish between interference and diffraction phenomena. Derive the expression for the intensity at a point of the interference pattern in Young's double-slit experiment.

Why are multiple colours observed over a thin film of oil floating on water? Explain with the help of a diagram.

Answer in brief:

Explain what is the optical path length. How is it different from actual path length?

Answer in brief:

What is meant by coherent sources?

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 the conditions for obtaining a good interference pattern? Give reasons.

What are the two methods for obtaining coherent sources in the laboratory?

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)?

The intensity of the light coming from one of the slits in Young's experiment is twice the intensity of the light coming from the other slit. What will be the approximate ratio of the intensities of the bright and dark fringes in the resulting interference pattern?

Two coherent sources whose intensity ratio is 25:1 produce interference fringes. Calculate the ratio of amplitudes of light waves coming from them.

Why two light sources must be of equal intensity to obtain a well-defined interference pattern?

Draw a neat labelled ray diagram of the Fresnel Biprism experiment showing the region of interference. 

What is interference?

Describe geometry of the Young’s double slit experiment with the help of a ray diagram. What is fringe width? Obtain an expression of it. Write the conditions for constructive as well as destructive interference. 

What are coherent sources of light? 

Explain constructive and destructive interference with the help of a diagram?

One of Young’s double slits is covered with a glass plate as shown in figure. The position of central maximum will,

What is interference of light?

What is phase of a wave?

Obtain the relation between phase difference and path difference.

What is intensity (or) amplitude division?

How does wavefront division provide coherent sources?

What is a bandwidth of interference pattern?

Obtain the equation for resultant intensity due to interference of light.

Explain Young’s double-slit experimental setup and obtain the equation for path difference.

Obtain the equation for bandwidth in Young’s double slit experiment.

Two independent monochromatic sources cannot act as coherent sources, why?

Does diffraction take place at Young’s double-slit?

In Young’s double-slit experiment, 62 fringes are seen in the visible region for sodium light of wavelength 5893 Å. If violet light of wavelength 4359 Å is used in place of sodium light, then what is the number of fringes seen?

The ratio of maximum and minimum intensities in an interference pattern is 36 : 1. What is the ratio of the amplitudes of the two interfering waves?

Light of wavelength 600 nm that falls on a pair of slits producing interference pattern on a screen in which the bright fringes are separated by 7.2 mm. What must be the wavelength of another light which produces bright fringes separated by 8.1 mm with the same apparatus?

The light waves from two independent monochromatic light sources are given by, y1 = 2 sin ωt and y2 = 3 cos ωt. Then the correct statement is ____________.

Band width for red light of wavelength 6600 Å is 0.42 mm. If red Light is replaced by blue light of wavelength 4400 Å, then the change m bandwidth will be ____________.

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, 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 a biprism experiment, red light of wavelength 6500 Å was used. It was then replaced by green light of wavelength 5200 Å. The value of n for which (n + 1)th green bright band would coincide with nth red bright band for the same setting 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 biprism experiment, if the 5th bright band with wavelength 'λ1' coincides with the 6th dark band with wavelength 'λ2' then the ratio `(lambda_2/lambda_1)` is ______ 

If two light waves reaching a point produce destructive interference, then the condition of phase difference is ______

In Young's double-slit experiment, if the two sources of light are very wide, then ______.

In Young's double slit experiment, for wavelength λ1 the nth bright fringe is obtained at a point P on the screen. Keeping the same setting, source of light is replaced by wavelength λ2 and now (n + 1)th bright fringe is obtained at the same point P on the screen. The value of n is ______.

If we have two coherent sources S1 and S2 vibrating in phase, then for an arbitrary point P constructive interference is observed whenever the path difference 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 ______.

How will the interference pattern of Young's double slit change if one of the two slits is covered by a paper which transmits only half of the light intensity?

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.

In a double-slit experiment, the optical path difference between the waves coming from two coherent sources at a point P on one side of the central bright is 7.5 µm and that at a point Q on the other side of the central bright fringe and 1.8 µm. How many bright and dark fringes are observed between points P and Q if the wavelength of light used is 600 nm?

Describe Young's double-slit interference experiment.

With a neat labelled ray diagram explain the use of Fresnel's biprism to obtain two coherent sources.

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 30 bright band from the central bright band will be ______.


      Forgot password?
Use app×