Main Points

Human Eye

  • Human eye is in the shape of spherical ball and is composed of cornea, iris, pupil, lens and retina.
  • Human eyes can see nearby objects as well as distant objects with equal ease. This capability of the human eyes is called the power of accommodation.
  • The field of vision with a single eye is about 150o. On the other hand, the field of vision with two eyes is about 180o.
  • Myopia is also called near-sightedness because a person suffering from myopia can clearly see a nearby object but finds it difficult to see a distant object.
  • Hypermetropia is also called far-sightedness because a person suffering from hypermetropia can clearly see distant objects but finds it difficult to see a nearby object.
  • After a certain age, most of the people find it difficult to clearly see a nearby object. This condition is called presbyopia.
  • In case of a triangular prism, the emergent ray is at an angle to the incident ray.
  • Splitting of white light into its component colours is called dispersion of light.
  • Rainbow formation happens because of refraction, dispersion and total internal reflection of light.
  • Twinkling of stars, advanced sunrise and delayed sunset happen because of atmospheric refraction.
  • When a ray of light strikes a small particle then it bends from its path. This phenomenon is called scattering of light.
  • When light passes through a colloid, then a beam of light is visible because of scattering of light. This phenomenon is called Tyndall effect.

These main points are highly helpful for last minute preparation for examination. You can glance through them while going for examination. You can view them in the school bus, in car, in elevator, etc.