Question

The E.N.T. (Ear, Nose and Throat) specialist uses a:
(A) Convex mirror
(B) Convex lens
(C) Plane mirror
(D) Concave mirror

Answer 1

Hint : In this question it has been asked that the E.N.T. a specialist uses what kind of mirror or lenses to diagnose the defect in the ear, nose and throat. To answer this question we must have the proper knowledge of the mirrors and lenses, and the images formed by them. For diagnosis of ear, nose and throat the image must be real and enlarged.

Complete Step By Step Answer:
Let us discuss about all the options above
Convex mirror: It is a type of mirror that bulges towards the light source. So, this surface reflects the light outwards and the image forms inside the mirror and the image looks smaller than that of the object which is not useful for the diagnosis. Thus, this option is cancelled out.
Convex lens: It is made up of two spherical mirrors and both of them are bulging outwards. These lenses converge the coming light rays on the other point on the principal axis of the lens. The point where the rays are converged is known as focus. The image formed by this lens is diminished, inverted and virtual. Image is real or virtual depending on the position of the object. The diminished image is not required by the specialist as it would make him difficult to recognize the defect. Hence, this option is also rejected.
Plane mirror: It forms the real image and of the same size as that of the object. As we have known that the requirement of a specialist is real or virtual but large. So, this option is also rejected.
Concave mirror: It is a type of mirror which is bent inside just opposite of the convex mirror. The inner part is reflecting the surface. The convergence of light occurs at the point when it strikes and reflects back from the reflecting surface of the concave mirror. The image formed by this mirror is magnified and virtual, if we increase the distance between object and mirror the image formed is of reduced size and real. According to the requirement of the E.N.T. This mirror is perfect.
Therefore, the correct option is D.

Note :
Here, we have to be careful about the mirrors and lenses sometimes they confuse oneself. So, one must understand the difference between the mirror and lens and also the image formed by them. We go with option D as the concave mirror form enlarged and real or virtual image as required by the specialist.