A person who can see things most clearly at a distance of `10 cm`. Requires spectacles to enable to him to see clearly things at a distance of `30 cm.` What should be the focal length of the spectacles ?

A person who can see things most clearly at a distance of 10 cm , requires spectacles to be able to see clearly things at a distance of 30 cm . What should be the focal length of the spectacles ?

A person who can see objects clearly at a distance of 10cm , requires spectacles to be able to see clearly objects at a distance of 30 cm. what type of spectacle should he use? Find the focal length of the lens.

A Person who can see objects clearly at a distance of 10cm, required spectacles to be able ot see clearly objects at a distance of 30cm. What types of spectacle should he use? Find the focal length of the lens.

If a person can sees clearly at a distance of 100 cm, then find the power of leris used to see object at 40 cm.

If a person can sees clearly at a distance of 100 cm, then find the power of leris used to see object at 40 cm.

A person can not see the objects clearly placed at a distance more than 40 cm . He is advised to use a lens of power

A person can see clearly upto 1 m. The nature and power of the lens which will enable him to see things at a distance of 3 m is

The distance of distinct vision of a person is 50 cm. He wants to read a book placed at 25 cm. What should be the focal length of the spectacles ?