CBSE Physics Optics Expected Questions : Unit VIII
(Short/Very Short Answer Questions-1, 2 Marks)
1. Doppler effect can help to decide whether a star is approaching or receding from earth. Explain how ?
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2. If two slits in Young’s experiment have widths in the ratio of 16:1, calculate the ratio of intensity of maximum and minimum in interference pattern.
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3. If power of a lens is + 5 dioptre, what is its focal length ?
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4. Why does a soap bubble show beautiful colours when illuminated by white light.
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5. State the conditions for the two light waves to be coherent.
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6. Will the reflected ray converge at a point when a parallel beam of light is incident on a concave mirror of large aperture ?
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7. Light of wavelength 6,000 A in air enters a medium of refractive index 1.5. What will be its frequency in the medium ?
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8. Two thim lenses of focal length 15 cm and 30 cm respectively are kept in contact with each other. What is the power of the combined system ?
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9. Copy the following diagram and complete it to show the rays emerging out of prism B.
image 
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10. Describe with the aid of a labelled diagram, how the wavelength of monochromatic light may be found by Young’s double slit experiment.
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11. A slit of width a is illuminated by monochromatic light at normal incidence. Draw the intensity distribution curve due to diffraction.
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