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To observe diffraction, we need only a single slit, but for interference, we need two slits.

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Important Questions on Wave Optics

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Physics>Optics>Wave Optics>Diffraction of Light
In a diffraction pattern due to a single slit of width a the first minimum is observed at an angle 30o when light of wavelength 5000 Å is incident on the slit. The first secondary maximum is observed at an angle of:
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Physics>Optics>Wave Optics>Diffraction of Light
A Fraunhofer diffraction pattern due to a single slit of width 0.3 mm is obtained on a screen placed at a distance of 3 m from the slit. The first minima lie at 5.5 mm on either side of the central maximum on the screen. The wavelength of light used is
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Physics>Optics>Wave Optics>Diffraction of Light
Light travels in a straight line because
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Physics>Optics>Wave Optics>Diffraction of Light
In a Fraunhofer diffraction at a single slit, if yellow light illuminating the slit is replaced by blue light, then diffraction bands
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Physics>Optics>Wave Optics>Diffraction of Light
A beam of light of λ=600 nm from a distant source falls on a single slit 1 mm wide and the resulting diffraction pattern is observed on a screen 2 m away. The distance between first dark fringes on either side of the central bright fringe is:
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Physics>Optics>Wave Optics>Diffraction of Light
The bending of beam of light around corners of obstacles is called
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Physics>Optics>Wave Optics>Diffraction of Light
A parallel beam of monochromatic light falls normally on a single narrow slit. The angular width of the central maximum in the resulting diffraction pattern
HARD
Physics>Optics>Wave Optics>Diffraction of Light
Monochromatic light of wavelength 4300 Å falls on a slit of width ‘a’. For what value of ‘a’ the first maximum falls at 30°?
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Physics>Optics>Wave Optics>Diffraction of Light
At the first minimum adjacent to the central maximum of a single-slit diffraction pattern, the phase difference between the Huygen's wavelet from the edge of the slit and the wavelet from the midpoint of the slit is:
MEDIUM
Physics>Optics>Wave Optics>Diffraction of Light

In the figure below, P and Q are two equally intense coherent sources emitting radiation of wavelength 20m. The separation between P and Q is 5m and the phase of P is ahead of that of Q by 90°.A,B and C are three distinct point of observation, each equidistant from the midpoint of PQ. The intensities of radiation at A,B,C will be in the ratio :

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MEDIUM
Physics>Optics>Wave Optics>Diffraction of Light
A plane wavefront of wavelength λ is incident on a single slit of width a. The angular width of the principal maximum is
MEDIUM
Physics>Optics>Wave Optics>Diffraction of Light
A single slit of width 0.1 mm is illuminated by a parallel beam of light of wavelength 6000 Å and diffraction bands are observed on a screen 0.5 m from the slit. The distance of the third dark band from the central bright band is:
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Physics>Optics>Wave Optics>Diffraction of Light
The penetration of light into the region of geometrical shadow is called
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Physics>Optics>Wave Optics>Diffraction of Light
A parallel beam of electrons travelling in x - direction falls on a slit of width d (see figure). If after passing the slit, an electron acquires momentum py in the y - direction then for a majority of electrons passing through the slit (h is Planck's constant):

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Physics>Optics>Wave Optics>Diffraction of Light
Which is the following colourful patterns is due to diffraction of light?
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Physics>Optics>Wave Optics>Diffraction of Light
Light of wavelength 550 nm falls normally on a slit of width 22.0×10-5 cm. The angular position of the second minima from the central maximum will be (in radians):
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Physics>Optics>Wave Optics>Diffraction of Light
A diffraction pattern is obtained by making blue light incident on a narrow slit. If blue light is
replaced by red light, then the diffraction bands _______.
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Physics>Optics>Wave Optics>Diffraction of Light
When a light of wavelength 6328 Ao is incident on a slit of width 0.2 mm perpendicularly, the angular width of central maxima will be ___.
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Physics>Optics>Wave Optics>Diffraction of Light
The box of a pin hole camera, of length L, has a hole of radius a. It is assumed that when the hole is illuminated by a parallel beam of light of wavelength λ the spread of the spot (obtained on the opposite wall of the camera) is the sum of its geometrical spread and the spread due to diffraction. The spot would then have its minimum size (say bmin ) when:
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Physics>Optics>Wave Optics>Diffraction of Light
For a parallel beam of monochromatic light of wavelength λ, diffraction is produced by a single slit whose width a is of the order of the wavelength of the light. If D is the distance of the screen from the slit, the width of the central maxima will be: