Question

Which of the following terms is not associated with a lens?
A) Aperture
B) Focal length
C) Principal focus
D) Efficiency

Answer 1

Hint: Lenses are the pieces of transparent material. Lenses refract light in such a way that an image of the object is formed. So many terms related to lenses come into play. Like, principal axis, centre of curvature etc.

Complete step by step answer:
Lenses are the bits of straightforward material having one or the two sides are round. It is the straightforward material wherein two surfaces, of which at any rate one is curved. Lenses refract light with the end goal that a picture of the article is shaped. Each surface of a lens is an aspect of a circle. Normal kinds of lens, the convex lens, concave lens. .
Convex lens(focal point) these focal points are thick at the middle and slim from edges and it makes occurrence beams combine at a point so it is otherwise called converging lens or focal point.
Concave lens/focal point These kinds of focal points are meager at the middle and thick at the edges and they wander the episode equal beams and are known as diverging focal points.

Presently terms identified with lens are:
> Aperture: it is the width of its light communicating zone. In this way, the brilliance or the intensity of the picture framed by a lens which relies upon the measure of light going through the lens will change as of the aperture of the lens.
> Centre of curvature: it is of a focal point is the focal point of the empty circle of glass of which the lens is a section.
> Radius of curvature: it is the span of over which focal point/lens is a section.
> Principal axis: The line going through the two communities of curvature of the focal point is called principal axis.
> Principal focus: The light beams heading out corresponding to the principal axis of a convex lens after refraction meet at a point on the principal axis, called principal focus of point of convergence.
> Focal length:  This is the separation between the optical centre and the principal focus interest.
Efficiency is characterized as the capacity to create something with a base measure of effort. An example of efficiency is a decrease in the quantity of laborers expected to make a vehicle.
So option D is correct.

Note: Always remember the difference between lens and mirrors. Don’t confuse convergence and diverging and also understand the difference of focus and focal length. ALso efficiency is a term generally used when some form of energy transformation is involved and in case of lenses there is no case of energy transformation.