An elderly person is facing difficulty while reading a book which is about 25cm distance from his eyes. Name the eye defect from which the person is suffering.

A person is able to see objects clearly only when these are lying at a distance between 50 cm and 300 cm from his eye. (a) What kind of defects of vision is he suffering from ? (b) What kind of lenses are required to increases his range of vision from 25 cm to infinity ? Explain briefly.

A tangent is drawn to a circle of radius 8 cm from a point which is at a distance of 10 cm from the centre of the circle.Then the length of the tangent is:

A person is wearing spectacles which is (i) thicker at the centre (ii) thinner at the centre and (iii) made of two different types of lenses. Identify the type of lens and the defect of vision the person is suffering from, in each case.

An old man is advised by his doctor to take less sugar in his diet. Name the disease from which the man is suffering. Mention the hormone due to imbalance of which he is suffering from this disease. Which endocrine gland secretes this hormone ?

A person wants to read a book placed at 20 cm whereas the near poit of his eyes is 50 cm. Calculate the power of the lens required.