Advertisements
Advertisements
प्रश्न
Explain the following term related to spherical lenses:- principal focus
Advertisements
उत्तर
Principal Focus:-
The convex lens converge the rays incident on it after refraction, to a point on the principal axis. This point is known as principal focus of the convex lens. The rays incident on concave lens appear to diverge from a point on the principal axis. This point is known as the principal focus of concave lens.
APPEARS IN
संबंधित प्रश्न
A student focused the Sun rays using an optical device 'X' on a screen S as shown.
From this it may be concluded that the device 'X' is a (select the correct option)
(A) Convex lens of focal length 10 cm.
(B) Convex lens of radius of curvature 20 cm.
(C) Convex lens of focal length 20 cm.
(D) Concave mirror of focal length 20 cm.
When a spherical mirror is held towards the sun and its sharp image is formed on a piece of a carbon paper for some time, a hole is burnt in the carbon paper.
Why is a hole burnt in the carbon paper?
When a spherical mirror is held towards the sun and its sharp image is formed on a piece of a carbon paper for some time, a hole is burnt in the carbon paper.
What is the advantage of using a carbon paper rather than a white paper?
State the two kinds of spherical mirror and distinguish them with the aid of proper diagrams.
Name the mirrors shown in Figure (a) and (b).
Why does a driver use a convex mirror instead of a plane mirror as a rear view mirror?
Illustrate your answer with the help of a ray diagram.
A real and enlarged image can be obtained by using a
The radius of curvature of a spherical mirror is 18 cm. What is the focal length of this mirror?
A spherical mirror whose reflecting surface is curved outwards is called ______ mirror.
