English Medium कक्षा १० - CBSE Question Bank Solutions for Science

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

What is the other name for 

 hypermetropia

What is the scientific name of 

short-sightedness

What is the scientific name of 

long-sightedness?

Name the defect of vision in which the eye-lens loses its power of accommodation due to old age.

Name the defect of vision which makes the eye-lens cloudy resulting in blurred vision.

What is the other name of old age hypermetropia?

Name any two defects of vision which can be corrected by using spectacles.

Name one defect of vision (or eye) which cannot be corrected by any type of spectacle lenses.

Name the body part with which the terms myopia and hypermetropia are connected.

What is the far point of a person suffering from myopia (or short-sightedness)?