Ranjini makes arrangements for a candle-light dinner and tops it with a dessert of elatine filled blue berries. If a blueberry that appears at an angle of 45^o to the normal in air is really located at 30^o to the normal in elatine, what is the index of refraction of the elatine?

Murugan trims his beard while looking into a concave mirror whose focal length is

18 cm. He looks into it from a distance of 12 cm.

i) How far is Murugan’s image from the mirror?

ii) Does it matter whether or not Murugan’s face is closer or farther than the focal length? Explain.

Light travels at 1.90 x 10⁸ m/s in a crystal, what is the crystal’s index of refraction?

If the far point of a myopic person is 75 cm, what should be the focal length of the lens used to rectify this defect?

Reena and Vani find a discarded plastic lens lying on the beach. The girls’ discuss what they learnt in Physics and argue whether the lens is a converging or diverging one. When they look through the lens, they notice that the objects are inverted.

i) If an object 25 cm in front of the lens forms an image 20 cm behind the lens, what is the focal length of the lens?

ii) Is it a converging or diverging lens?