A star emitting light of wavelength 5896 Å is moving away from the earth with a speed of 3600 km/sec. The wavelength of light observed on earth will 

(1) Decrease by 5825.25 Å

(2) Increase by 5966.75 Å

(3) Decrease by 70.75 Å

(4) Increase by 70.75 Å

(c = 3 × 108 m/sec is the speed of light)

Subtopic:  Superposition Principle |
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A heavenly body is receding away from the earth such that the fractional change in λ is 1, then its velocity is :

(1) C

(2) 3C5

(3) C5

(4) 2C5

Subtopic:  Superposition Principle |
 70%
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What will be the angular width of central maxima in Fraunhoffer diffraction when light of wavelength 6000Å is used and slit width is 12×10–5 cm 

(1) 2 rad

(2) 3 rad

(3) 1 rad

(4) 8 rad

Subtopic:  Diffraction |
 73%
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The direction of the first secondary maximum in the Fraunhofer diffraction pattern at a single slit is given by:
\((a\) is the width of the slit) 
1. \(a\sin\theta = \frac{\lambda}{2}\)
2. \(a\cos\theta = \frac{3\lambda}{2}\)
3. \(a\sin\theta = \lambda\)
4. \(a\sin\theta = \frac{3\lambda}{2}\)

Subtopic:  Diffraction |
 71%
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A parallel monochromatic beam of light is incident normally on a narrow slit. A diffraction pattern is formed on a screen placed perpendicular to the direction of the incident beam. At the first minimum of the diffraction pattern, the phase difference between the rays coming from the edges of the slit is:
1. \(0\)
2. \(\dfrac \pi 2 \)
3. \(\pi\)
4. \(2\pi\)

Subtopic:  Diffraction |
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A parallel beam of monochromatic light of wavelength \(5000~\mathring{A}\) is incident normally on a single narrow slit of width \(0.001\) mm. The light is focused by a convex lens on a screen placed on the focal plane. The first minimum will be formed for the angle of diffraction equal to:
1. \(0^{\circ}\)
2. \(15^{\circ}\)
3. \(30^{\circ}\)
4. \(60^{\circ}\)

Subtopic:  Diffraction |
 74%
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In the far field diffraction pattern of a single slit under polychromatic illumination, the first minimum 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

Subtopic:  Diffraction |
 79%
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The angle of polarisation for any medium is \(60^\circ,\) what will be the critical angle for this?

1. \( \sin ^{-1} \sqrt{3} \) 2. \( \tan ^{-1} \sqrt{3} \)
3. \(\cos ^{-1} \sqrt{3}\) 4. \(\sin ^{-1} \frac{1}{\sqrt{3}}\)

Subtopic:  Polarization of Light |
 64%
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A beam of light AO is incident on a glass slab (μ = 1.54) in a direction as shown in figure. The reflected ray OB is passed through a Nicol prism on viewing through a Nicole prism, we find on rotating the prism that, 

      

1. the intensity is reduced down to zero and remains zero.
2. the intensity reduces down some what and rises again.
3. there is no change in intensity.
4. the intensity gradually reduces to zero and then again increases.

Subtopic:  Polarization of Light |
 57%
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In the propagation of electromagnetic waves, the angle between the direction of propagation and plane of polarisation is:

(1) 0o

(2) 45o

(3) 90o

(4) 180o

Subtopic:  Polarization of Light |
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