Question

NAG VIDHYASHRAM SR. SEC.SCHOOL

UNIT TEST - IV

CLASS : X STD

SUBJECT : SCIENCE

MARKS : 25

TIME : 45 MINUTES

I. Answer the following questions :-

1. State the laws of reflection of light (2)

2. Define the principal focus of a concave mirror.(1)

3. Find the focal length of a convex mirror whose radius of curvature is 32 cm. (1)

4. Draw the virtual and erect enlarged image formed by a concave mirror and also write position of the object and position of the image .​

Answer 1

1.Following are the laws of reflection:

•The incident ray, the reflected ray and the normal to the surface of the mirror all lie in the same plane.

•The angle of incidence is equal to the angle of reflection.

2.The principle focus of concave mirror is a point on its principle axis to which all the light rays which are parallel and close to the axis, converge after reflection from the mirror.

3.As we know that the focal length of a spherical mirror is equal to half the radius of curvature of that mirror. So, according to your question the radius of curvature of a convex mirror is 32cm. 16 cm. So the focal length of the convex mirror is 16cm.