If a person can't see the object that is placed at a distance less than 50 cm, then what type of defect he is suffering from? Also tell the nature of lens and calculate the power of the lens so that he can clearly see the object that is placed at 25 cm from the eye.

If a person can't see the object that is placed at a distance less tha

1.	If a person can't see the object that is placed at a distance less than 50 cm, then what type of defect he is suffering from? Also tell the nature of lens and calculate the power of the lens so that he can clearly see the object that is placed at 25 cm from the eye.
Answer» SOLUTION :Defect from which the PERSON suffering=Long sightedness Given VALUE of u=-25cm Value of v=-50cm Use the lens formula (1/v)+(1/u)=1/f Put the VALUES of u and v in the above given formula (1/-50)+(1/-25)=1/f f=50cm =5m Power of lens=2D To correct this defect, convex lens with power 2D is required to be used.