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Set 3 of 18 · Questions 61-90 of 521

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JEE Main Physics · Ray Optics · Set 3 (Q61-90)

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  1. 61.
    A convex lens of focal length ' ' is placed somewhere in between an object and a screen. The distance between the object and the screen is ' '. If the numerical value of the magnification produced by the lens is ' ' then the focal length of the lens is
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  2. 62.
    A ray of laser of a wavelength 630nm is incident at an angle of at the diamond-air interface. It is going from diamond to air. The refractive index of diamond is 2.42 and that of air is 1. Choose the correct option.
    1. (1)angle of refraction is 24.
    2. (2)angle of refraction is
    3. (3)refraction is not possible
    4. (4)angle of refraction is 53.
  3. 63.
    A convex lens of focal length is placed in contact with a concave lens of the same focal length. The equivalent focal length of the combination will be
    1. (1)
    2. (2)infinity
    3. (3)
    4. (4)zero
  4. 64.
    A thin prism having refracting angle is made of glass of refractive index 1.42. This prism is combined with another thin prism of glass of refractive index 1.7. This combination produces dispersion without deviation. The refracting angle of second prism should be [NEET 2017]
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  5. 65.
    The speed of light in media and are and respectively. A ray travels from medium to the medium with an angle of incidence . The ray suffers total internal reflection. Then the value of the angle of incidence is
    1. (1)
    2. (2)
    3. (3)
    4. (4)≤sin-143
  6. 66.
    Four lenses of focal length cm and cm are available for making a telescope. To produce the largest magnification, the focal length of the eyepiece should be
    1. (1)
    2. (2)
    3. (3)
    4. (4).
  7. 67.
    An under-water swimmer cannot see very clearly even in absolutely clear water because of
    1. (1)Absorption of light in water
    2. (2)Scattering of light in water
    3. (3)Reduction of speed of light in water
    4. (4)Change in the focal length of eye lens
  8. 68.
    A man can see clearly up to 3 metres. Prescribe a lens for his spectacles so that he can see clearly up to 12 metres
    1. (1)– 3/4 D
    2. (2)3 D
    3. (3)– 1/4 D
    4. (4)– 4 D
  9. 69.
    If the refractive index of the material of a prism is , where is the angle of prism then the angle of minimum deviation will be
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  10. 70.
    A man who cannot see clearly beyond 5 m wants to see stars clearly. He should use a lens of focal length
    1. (1)– 100 m
    2. (2)+ 5 m
    3. (3)– 5 m
    4. (4)Very large
  11. 71.
    Two transparent media A and B are separated by a plane boundary. The speed of light in those media are and , respectively. The critical angle for a ray of light for these two media is [NEET 2022]
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  12. 72.
    Surface of certain metal is first illuminated with light of wavelength and then, by light of wavelength It is found that the maximum speed of the photo electrons in the two cases differ by a factor of The work function of the metal (in ) is close to: (Energy of photon )
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  13. 73.
    A plano convex lens of refractive index and focal length is kept in contact with another plano concave lens of refractive index and focal length If the radius of curvature of their spherical faces is each and then and are related as:
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  14. 74.
    Given below are two statements :
    Statement I : When the white light passed through a prism, the red light bends lesser than yellow and violet.
    Statement II : The refractive indices are different for different wavelengths in dispersive medium. In the light of the above statements, chose the correct answer from the options given below:
    1. (1)Statement I is false but Statement II is true
    2. (2)Statement I is true but Statement II is false
    3. (3)Both Statement I and Statement II are true
    4. (4)Both Statement I and Statement II are false
  15. 75.
    The image formed by a convex mirror of focal length is a quarter of the size of the object. The distance of the object from the mirror is
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  16. 76.
    A ray is incident from a medium of refractive index 2 into a medium of refractive index 1 . The critical angle is
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  17. 77.
    An object is placed at a distance of in front of a concave mirror of focal length . The image produced is
    1. (1)real, inverted and smaller in size
    2. (2)real, inverted and of same size
    3. (3)real and erect
    4. (4)virtual and inverted
  18. 78.
    Ratio of intensities of two waves are given by4: 1. nen ratio of the amplitudes of the two waves is
    1. (1)2: 1
    2. (2)1 : 2
    3. (3)4: 1
    4. (4)1 : 4.
  19. 79.
    There is a small source of light at some depth below the surface of water (refractive index ) in a tank of large cross sectional surface area. Neglecting any reflection from the bottom and absorption by water, percentage of light that emerges out of surface is (nearly):[Use the fact that surface area of a spherical cap of height and radius of curvature is ]
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  20. 80.
    The angle of deviation produced by a thin prism when placed in air is ' ' and that when immersed in water is ' . The refractive index of glass and water are and respectively. The ratio is
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  21. 81.
    A light ray travels from a medium with refractive index to another medium of refractive index . If and , then find the critical angle.
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  22. 82.
    In parallax method for the determination of focal length of a concave mirror, the object should always be placed:
    1. (1)between the focus (F) and the centre of curvature of the mirror ONLY
    2. (2)between the pole() and the focus () of the concave mirror ONLY
    3. (3)beyond the centre of the curvature of the mirror ONLY
    4. (4)at any point beyond the focus of the mirror
  23. 83.
    Light travels through a glass plate of thickness and having a refractive index If is the velocity of light in vacuum, the time taken by light to travel this thickness of glass is
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  24. 84.
    A ray of light passes through an equilateral glass prism in such a mamner that the angle of incidence is equal to the angle of emergence and each of these angles is equal to of the angle of the prism. The angle of deviation is
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  25. 85.
    A focal length of a lens is . What is power of a lens in dioptre?
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  26. 86.
    A ray of light travelling in a transparent medium of refractive index , falls on a surface separating the medium from air at an angle of incidence of . For which of the following value of , the ray can undergo total internal reflection?
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  27. 87.
    Two beams of red and violet colours are made to pass separately through a prism of . In the minimum deviation position, the angle of refraction inside the prism will be
    1. (1)greater for red colour
    2. (2)equal but not for both the colours
    3. (3)greater for violet colour
    4. (4) for both the colours.
  28. 88.
    The frequency of a light ray is . Its frequency when it propagates in a medium of refractive index 1.5, will be
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  29. 89.
    A travelling microscope is used to determine the refractive index of a glass slab. If 40 divisions are there in 1 cm on main scale and 50 Vernier scale divisions are equal to 49 main scale divisions, then least count of the travelling microscope is m.
  30. 90.
    The size of the images of an object, formed by a thin lens are equal when the object is placed at two different positions 8 cm and 24 cm from the lens. The focal length of the lens is cm .