Q1 State the laws of refraction. Distinguish between absolute refractive index and refractive index of a medium. Show that n=c/v, where letters have usual meanings. Solution

Q2 Explain why does a swimming pool appears shallower than it actually is. Obtain an expression for the normal displacement of an object immersed in water. Solution

Q3 Explain, with ray-diagram, total internal reflection of light. Give two conditions for it to take place. Obtain relation between critical angle and refractive index of the denser medium. Solution

Q4 A ray of light while travelling from a denser to a rarer medium undergoes total internal reflection. Deduce expression for the critical angle in terms of the speeds of light in the respective media. Solution

Q5 Show, by ray-diagrams, how a totally reflecting glass prism can be used to deviate a ray through
(i) 90∘ (ii) 180∘ . Solution

Q6 What is an optical fibre? On what principle does it work? Explain by ray-diagram, how optical fibres transmit signals. Mention one practical application of optical fibres. Solution