Question :List two differences in the characteristic properties of the virtual images formed by the two types of spherical lenses (concave and convex). How are these characteristics of the two lenses used in the correction of the two common defects of vision namely myopia and hypermetropia?
The correct answer is -Two differences in the characteristic properties of the virtual images formed by concave and convex lenses are:
-
Concave lenses always form virtual, erect and smaller images, while convex lenses can form virtual, erect, and magnified or real, inverted, and magnified images depending on the position of the object.
-
The position of the virtual image formed by a concave lens is always behind the lens, while the position of the virtual image formed by a convex lens can be in front of, behind or at the same position as the lens.
The characteristic properties of concave and convex lenses are used in the correction of myopia and hypermetropia as follows:
-
Myopia: In this condition, the person is unable to see distant objects clearly. A concave lens is used to correct myopia as it diverges the light rays before they enter the eye, thereby making the virtual image formed on the retina.
-
Hypermetropia: In this condition, the person is unable to see nearby objects clearly. A convex lens is used to correct hypermetropia as it converges the light rays before they enter the eye, thereby making the virtual image formed on the retina.
