Question

Myopia of the common defects of vision and the type of lens used to remove it is:

Answer 1

Hint:Myopia is the defect of eye in which the person with Myopia can see the nearby objects clearly but the distant objects appear blurred to him. The eye with myopia is not able to focus the light ray into the retina but the image is formed in front of the retina. Recall the lens which can diverge the rays.

Complete answer:
As we know Myopia is also known as nearsightedness which is the defect of the eye in which the person with Myopia can see the nearby objects clearly but the distant objects appear blurred to him. This condition appears in about one third of the population. In myopia, the eye of a person has too much focusing power either due to the eye being too long or due to a more curved cornea. Therefore, when someone with myopia tries to look at the distant object, the rays of light focus in front of the retina rather than being focused onto it. Thus, we can see, the image of that object gets blurred.

Since the person with myopia cannot focus the light rays reflected from the distant object, we can use a proper lens to focus the light rays onto the retina. The concave lens which forms a virtual image of the object is used to cure myopia. The concave lens forms a real image onto the retina and a virtual image of the object at the far point of the eye and the person can see the virtual image from the lens.

So, the myopia can be removed using the concave lens.

Note: The concave lens is used to form a virtual image while the convex lens is used to form a real image. The concave lens diverges the parallel rays falling onto it while the convex lens converges the parallel rays falling onto it. We cannot use a convex lens to cure myopia since the convex lens converges the ray onto the lens of an eye and thus the image will not be formed.