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Optics Model Question Paper

12th Standard

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Physics

Time : 00:45:00 Hrs
Total Marks : 35
    10 x 1 = 10
  1. For light incident from air on a slab of refractive index 2, the maximum possible angle of refraction is, ______.

    (a)

    30o

    (b)

    45o

    (c)

    60o

    (d)

    90o

  2. If the velocity and wavelength of light in air is Va and λa and that in water is Vw and λw, then the refractive index of water is______.

    (a)

    \(\frac{V_W}{V_a}\)

    (b)

    \(\frac{V_a}{V_W}\)

    (c)

    \(\frac{\lambda_W}{\lambda_a}\)

    (d)

    \(\frac{{V_a}\lambda_a}{{V_W}\lambda_W}\)

  3. When a biconvex lens of glass having refractive index 1.47 is dipped in a liquid, it acts as plane sheet of glass. This implies that the liquid must have refractive index, ______.

    (a)

    less than one

    (b)

    less than that of glass

    (c)

    greater than that of glass

    (d)

    equal to that of glass

  4. The radius of curvature of curved surface at a thin planoconvex lens is 10 cm and the refractive index is 1.5. If the plane surface is silvered, then the focal length will be, ______.

    (a)

    5 cm

    (b)

    10 cm

    (c)

    15 cm

    (d)

    20 cm

  5. A plane glass is placed over a various coloured letters (violet, green, yellow, red) The letter which appears to be raised more is _____.

    (a)

    red

    (b)

    yellow

    (c)

    green

    (d)

    violet

  6. Two coherent monochromatic light beams of intensities I and 4I are superposed. The maximum and minimum possible intensities in the resulting beam are _____.

    (a)

    5I and I

    (b)

    5I and 3I

    (c)

    9I and I

    (d)

    9I and 3I

  7. When light is incident on a soap film of thickness 5 x 10–5 cm, the wavelength of light reflected maximum in the visible region is 5320 Å. Refractive index of the film will be, _____.

    (a)

    1.22

    (b)

    1.33

    (c)

    1.51

    (d)

    1.83

  8. A ray of light strikes a glass plate at an angle 60o. If the reflected and refracted rays are perpendicular to each other, the refractive index of the glass is, _____.

    (a)

    \(\sqrt3\)

    (b)

    \(\frac{3}{2}\)

    (c)

    \(\sqrt{\frac{3}{2}}\)

    (d)

    2

  9. Light transmitted by Nicol prism is, _____.

    (a)

    partially polarised

    (b)

    unpolarised

    (c)

    plane polarised

    (d)

    elliptically polarised

  10. The transverse nature of light is shown in,

    (a)

    interference

    (b)

    diffraction

    (c)

    scattering

    (d)

    polarisation

  11. 5 x 2 = 10
  12. What is principle of reversibility?

  13. Why do stars twinkle?

  14. Explain the reason for the glittering of diamond.

  15. What is Snell’s window?

  16. What are the sign conventions followed for lenses?

  17. 5 x 3 = 15
  18. Obtain the equation for lateral displacement of light passing through a glass slab.

  19. Derive the equation for refraction at single spherical surface.

  20. Obtain lens maker’s formula and mention its significance.

  21. Derive the equation for angle of deviation produced by a prism and thus obtain the equation for refractive index of material of the prism.

  22. What is dispersion? Obtain the equation for dispersive power of a medium.

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