Due to a gradual weakening of ciliary muscles and diminishing flexibility of the eye lens a certain defect of vision arises. Write the name of this defect. Name the type of lens required by such persons to improve the vision. Explain the structure and function of such a lens.
The type of lens required by such person to improve the vision is the bifocal lens.
A bifocal lens consists of both convex lens and concave lenses. The convex lens used in the bifocal lens is used to correct hypermetropia (far sightedness) and a concave lens is used to correct myopia (short sightedness).
Why do the component colours of incident white light split into a spectrum while passing through a glass prism, explain?
How do Mendel’s experiments show that
Inheritance of two traits is independent of each other?
Name the organ that produces sperms as well as secretes a hormone in human males. Name the hormone it secretes and writes its functions.
You have been selected to talk on “ozone layer and its protection” in the school assembly on ‘Environment Day.’
(a) Why should ozone layer be protected to save the environment?
(b) List any two ways that you would stress in your talk to bring in awareness amongst your fellow friends that would also help in the protection of ozone layer as well as the environment.
A concave mirror produces three times magnified image on a screen. If the object is placed 20 cm in front of the mirror, how far is the screen from the object?
