Light waves of intensities \(I\) and \(9I\) interfere to produce a fringe pattern on a screen. The phase difference between the waves at point P is and 2 at other point Q. The ratio of intensities at P and Q is:
1. 8: 5
2. 5: 8
3. 1: 4
4. 9: 1
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Two coherent sources are 0.3 mm apart. They are 1 m away from the screen. The second dark fringe is at a distance of 0.3 cm from the center. The distance of the fourth bright fringe from the centre is:
1. 0.6 cm
2. 0.8 cm
3. 1.2 cm
4. 0.12 cm
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Huygens' wave theory allows us to know the:
1. | Wavelength of the wave. |
2. | Velocity of the wave. |
3. | Amplitude of the wave. |
4. | Propagation of wavefront. |
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Two light sources are said to be coherent when their:
1. | amplitudes are equal and have a constant phase difference. |
2. | wavelengths are equal. |
3. | intensities are equal. |
4. | frequencies are equal and have a constant phase difference. |
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Five identical polaroids are placed coaxially with \(45^{\circ}\) angular separation between pass axes of adjacent polaroids as shown in the figure. (I0: Intensity of unpolarized light)
The intensity of light, I,
emerging out of the 5th polaroid is:
1.
2.
3.
4.
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If the polarising angle for a material is , then the refractive index of the material will be:
1.
2.
3.
4.
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On superposition of two waves \(y_{1}=3sin\left ( \omega t-kx \right )\) and \(y_{2}=4sin\left ( \omega t-kx+\frac{\pi }{2} \right )\) at a point, the amplitude of the resulting wave will be:
1. 7
2. 5
3.
4. 6.5
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Unpolarized light of intensity 32 Wm–2 passes through three polarizers such that the transmission axes of the first and second polarizer make an angle of 30° with each other and the transmission axis of the last polarizer is crossed with that of the first. The intensity of the final emerging light will be:
1. 32 Wm–2
2. 3 Wm–2
3. 8 Wm–2
4. 4 Wm–2
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If we observe the single slit Fraunhofer diffraction with wavelength and slit width d, the width of the central maxima is 2. On decreasing the slit width for the same wavelength :
1. | θ increases. |
2. | θ remains unchanged. |
3. | θ decreases. |
4. | θ increases or decreases depending on the intensity of light. |
Two polaroids P1 and P2 are placed with their axis perpendicular to each other. Unpolarised light of intensity Io is incident on P1. A third polaroid P3 is kept in between P1 and P2 such that its axis makes an angle 45° with that of P1. The intensity of transmitted light through P2 is:
1.
2.
3.
4.
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