# Convex Mirror Viva Questions

Convex Mirror Experiment Viva Questions with Answers

(i) Define principal focus of a convex mirror.

Ans: Paraxial rays parallel to the principal axis after reflection at the convex mirror appear to diverge from a point. This point is the principal focus.

(ii) What is radius of curvature of a convex mirror?

Ans: It is the radius of the sphere of which the mirror forms a part.

(iii) What is the relation between radius of curvature and focal length?

Ans: r = 2f

(iv) An object is placed in front of a convex mirror. What is the nature of the image formed?

Ans: The image is virtual, erect diminished and formed with in the focus.

(v) What is the use of convex mirror?

Ans: It is used as rear view mirror for motor car. It offers wide field of view and the image is erect.

(vi) What is the radius of curvature of a plane mirror?

Ans: Infinity

(vii) Aim of Convex Mirror Experiment

To find the focal length of a convex mirror using a convex lens

(viii) Apparatus of Convex Mirror Experiment

Illuminated object (light box with a cross wire or wire gauze), convex mirror, convex lens, stands for mounting the mirror and lens, screen etc.

(ix) Theory of Convex Mirror Experiment

If r is the radius of curvature of the convex mirror, its focal length, f = r/2

(x) Procedure of Convex Mirror Experiment

The convex lens is placed in front of the illuminated object, the light box with a cross wire. A screen is adjusted until a clear image is formed on it. The convex mirror is now placed between the lens and the screen with its reflecting surface towards the lens. The mirror is adjusted in position until a clear image of the cross-wire is obtained on the surface of the light box side by side with the cross wire. The distance between the position of the convex mirror and the screen is measured. This gives the radius of curvature r of the mirror. The experiment is repeated with the illuminated objects at different distances from the lens and the average value of r is found out. Hence, f = r/2 is calculated.