A person uses spectacles of power +2D. What type of defect of vision is it?

A person using spectacles having power +2.5m^(-1) can see the objects distinctly at a distance of 25 cm . What is the near point for the person ? What type of defect of vision does the eye have ?

A person uses glass of power '+2D . He is suffering from-

A person with spectacles of power 3m ^(-1) can see distinctly the letters of newspaper placed at a distance of 25 cm from the eye. At what distance should the newspaper be kept to be able to read it without spectacles?

What type of mirror do dentists use ?

Which type of defect of vision is rectified a convex lens?

A short sighted person can see objects at 20cm from his eyes. What type of lens is to be used to see clearly objects at 100cm away?

By using the spectacles of a concave lens of power -5 m^(-1) a man can read a book keeping it at a distance of 30 cm from his eyes. Without spectacles what is his least distance of distinct vision ? What is the nature of defect in his eyes ?

A person is wearing spectacles with concave lenses for correcting vision. While not using the glasses, the image of a distant object in his case will be formed

(a) Analysis shows that a metal oxide has the empirical formula M_(0.96)O_(1.00) . Calculate the percentage of M^(2+)andM^(3+) ions in this crystal? (b) What type of defect is found in this crystal?