Wave Optics - NEET Physics Questions
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Wave Optics

Question 21: moderate

The ratio of intensities of consecutive maxima in the diffraction pattern due to a single slit is :

1. 1 : 4 : 9
2. 1 : 2 : 3
3. \[1:\frac{4}{9\pi^{2}}:\frac{4}{25\pi^{2}}\]
4. \[1:\frac{1}{\pi^{2}}:\frac{9}{\pi^{2}}\]
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Question 22: difficult

Two polaroids are placed in the path of unpolarised beam of intensity I0 such that no light is emitted from the second polarioid. If a third polaroid whose polarization axis makes an angle θ with the polarization axis of first polaroid, is placed between these polaroids then the intensity of light emerging from the last polaroid will be :

1. \[\frac{I_{0}}{8}sin^{2} 2\theta\]
2. \[\frac{I_{0}}{4}sin^{2} 2\theta\]
3. \[\frac{I_{0}}{2}cos^{4} \theta\]
4. \[I_{0}cos^{4} \theta\]
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Question 23: easy

Consider Fraunhoffer diffraction pattern obtained with a single slit at normal incidence. At the angular position of first diffraction minimum, the phase difference between the wavelets from the opposite edges of the slit is :

1. π/4
2. π/2
3. π
4.
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Question 24: easy

A single slit of width 0.20 mm is illuminated with light of wavelength 500 nm. The observing screen is placed 80 cm from the slit. The width of the central bright fringe will be :

1. 1 mm
2. 2 mm
3. 4 mm
4. 5 mm
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Question 25: moderate

A plane wavefront \[\left( \lambda=6\times 10^{-7}m \right)\] falls on a slit 0.4 mm wide. A convex lens of focal length 0.8m placed behind the slit focusses the light on a screen. What is the linear diameter of second maximum :

1. 6 mm
2. 12 mm
3. 3 mm
4. 9 mm
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Question 26: moderate

For what distance is ray optics a good approximation when the aperture is 4 mm wide and the wavelength is 500 nm :

1. 32 m
2. 64 m
3. 16 m
4. 8 m
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Question 27: moderate

A light wave is incident normally over a slit of width \[24\times 10^{-5} cm\]. The angular position of second dark fringe from the central maxima is 30 degree. What is the wavelength of light :

1. 6000 Å
2. 5000 Å
3. 3000 Å
4. 1500 Å
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Question 28: moderate

In the far field diffraction pattern of a single slit under polychromatic illumination, the first minima with the wavelength λ1 is found to be coincident with the third maximum at λ2. So :

1. 3λ1 = 0.3λ2
2. 3λ1 = λ2
3. λ1 = 3.5λ2
4. 0.3λ1 = 3λ2
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Question 29: moderate

A single slit of width a is illuminated by violet light of wavelength 400 nm and the width of the diffraction pattern is measured as y. When half of the slit width is covered and illuminated by yellow light of wavelength 600 nm, the width of the diffraction pattern is :

1. The pattern vanishes and the width is zero
2. y/3
3. 3y
4. None of these
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Question 30: moderate

Two polaroids are placed in the path of unpolarized beam of intensity I0 such that no light is emitted from the second polaroid. If a third polaroid whose polarization axis makes an angle θ with the polarization axis of first polaroid, is placed between these polaroids then the intensity of light emerging from the last polaroid will be :

1. \[\left( \frac{I_{0}}{8} \right)sin^{2} 2\theta\]
2. \[\left( \frac{I_{0}}{4} \right)sin^{2} 2\theta\]
3. \[\left( \frac{I_{0}}{2} \right)cos^{2} \theta\]
4. \[I_{0}cos^{4} \theta\]
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