(i) The radius of curvature of a concave mirror is 42 cm. What is its focal length? Find the distance at which image of an object placed at a distance of 6 cm from it will be formed. Also write the nature of the image so formed.
(ii) What is meant by the statement that the refractive index of diamond is 2.42?
(iii) Refractive index of water, kerosene, ice and glass are 1.33, 1.44, 1.31, and 1.5 respectively. Arrange these in decreasing order of optical density
