SolveItClass 10 · NCERT

NCERT Solutions · Class 10 Science The Human Eye and the Colourful World

12 questions · 12 still being checked

EXERCISES 1–12

  1. Exercise 1

    The human eye can focus on objects at different distances by adjusting the focal length of the eye lens. This is due to
    (a)
    presbyopia.
    (b)
    accommodation.
    (c)
    near-sightedness.
    (d)
    far-sightedness.
    NCERT’s answer
    (b)

    Working being prepared

  2. Exercise 2

    The human eye forms the image of an object at its
    (a)
    cornea.
    (b)
    iris.
    (c)
    pupil.
    (d)
    retina.
    NCERT’s answer
    (d)

    Working being prepared

  3. Exercise 3

    The least distance of distinct vision for a young adult with normal vision is about
    (a)
    25\displaystyle 25 m.
    (b)
    2.5\displaystyle 5 cm.
    (c)
    25\displaystyle 25 cm.
    (d)
    2.5\displaystyle 5 m.
    NCERT’s answer
    (c)

    Working being prepared

  4. Exercise 4

    The change in focal length of an eye lens is caused by the action of the
    (a)
    pupil.
    (b)
    retina.
    (c)
    ciliary muscles.
    (d)
    iris.
    NCERT’s answer
    (c)

    Working being prepared

  5. Exercise 5

    A person needs a lens of power –5.5\displaystyle 5.5 dioptres for correcting his distant vision. For correcting his near vision he needs a lens of power +1.5\displaystyle 1.5 dioptre. What is the focal length of the lens required for correcting
    (i)
    distant vision, and
    (ii)
    near vision?
    NCERT’s answer
    (i)
    –$\displaystyle 0.18$ m;

    Working being prepared

  6. Exercise 6

    The far point of a myopic person is 80\displaystyle 80 cm in front of the eye. What is the nature and power of the lens required to correct the problem?
    NCERT’s answer
    Concave lens; –$\displaystyle 1.25$ D

    Working being prepared

  7. Exercise 7

    Make a diagram to show how hypermetropia is corrected. The near point of a hypermetropic eye is 1\displaystyle 1 m. What is the power of the lens required to correct this defect? Assume that the near point of the normal eye is 25\displaystyle 25 cm.
    NCERT’s answer
    Convex lens; +$\displaystyle 3.0$ D

    Working being prepared

  8. Exercise 8

    Why is a normal eye not able to see clearly the objects placed closer than 25\displaystyle 25 cm?

    Solution being prepared

  9. Exercise 9

    What happens to the image distance in the eye when we increase the distance of an object from the eye?

    Solution being prepared

  10. Exercise 10

    Why do stars twinkle?

    Solution being prepared

  11. Exercise 11

    Explain why the planets do not twinkle.

    Solution being prepared

  12. Exercise 12

    Why does the sky appear dark instead of blue to an astronaut?

    Solution being prepared