English Medium Class 10 - CBSE Question Bank Solutions for Science

Complete the following sentence: 

All the distances are measured from the .......... of a spherical mirror. 

Write the mirror formula. Give the meaning of each symbol which occurs in it.

Name the spherical mirror which can produce a real and diminished image of an object.

Name the spherical mirror which can produce a virtual and diminished image of an object.

The shiny outer surface of a hollow sphere of aluminium of radius 50 cm is to be used as a mirror: 

 What will be the focal length of this mirror?

The shiny outer surface of a hollow sphere of aluminium of radius 50 cm is to be used as a mirror: 

 Which type of spherical mirror will it provide? 

The shiny outer surface of a hollow sphere of aluminium of radius 50 cm is to be used as a mirror: 

 State whether this spherical mirror will diverge or converge light rays.

Write the formula for a lens connecting image distance (v), object distance (u) and the focal length (f). How does the lens formula differ from the mirror formula?                         

A lens forms a real image 3 cm high of an object 1 cm high. If the separation of object and image is 15 cm, find the focal length of the lens.

A diverging lens is used in:
(a) a magnifying glass
(b) a car to see objects on rear side
(c) spectacles for the correction of short sight
(d) a simple camera

A 50 cm tall object is at a very large distance from a diverging lens. A virtual, erect and diminished image of the object is formed at a distance of 20 cm in front of the lens. How much is the focal length of the lens?

A 2.0 cm tall object is placed 40 cm from a diverging lens of focal length 15 cm. Find the position and size of the image.

A small object is placed 150 mm away from a diverging lens of focal length 100 mm.
(i) Copy the figure below and draw rays to show how an image is formed by the lens.
Figure
(ii) Calculate the distance of the image from the lens by using the lens formula.

 The diverging lens in part (a) is replaced by a converging lens also of focal length 100 mm. The object remains in the same position and an image is formed by the converging lens. Compare two properties of this image with those of the image formed by the diverging lens in part (a).

A concave lens produces an image 20 cm from the lens of an object placed 30 cm from the lens. The focal length of the lens is:
(a) 50 cm
(b) 40 cm
(c) 60 cm
(d) 30 cm

Name the defect of vision in a person: 

 whose near point is more than 25 on away.  

Name the defect of vision in a person: 

whose far point is less than infinity

 Which defect of vision can be rectified: 

by using a concave lens?

Which defect of vision can be rectified: 

 by using a convex lens?

What is the other name for 

 myopia