Collect the values of refractive index of the following media. (AS4)

Water, coconut oil, flint glass, crown glass, diamond. benzene and hydrogen gas.

Take a glass vessel and pour some glycerine into it and then power water upto the brim. Take a quartz glass rod. Keep it in the vessel. Observe the glass rod from the sides of the glass vessel.

• What changes do you notice?

• What could be the reasons for these changes? (AS2)

Do activity-7again. How can you find critical angle of water? Explain your steps briefly. (AS3)

Coiled information a working of optical fibers. Prepare a report about various uses of optical rubles in our daily life. (AS4)

Take a thin thermal sheet. Cut it in circular discs of different radii like 2cm, 3cm, 4cm, 4.5cm. 5cm etc ad mark centers with sketch pen. Now take needles of length nearly firm. Pin a needle to each disc at its centre vertically. Take water in a large opaque tray and place the disc with 2cm radius in such a way that the raw& is inside the water ac shown in fig Q15. Now try to view the free end (head) of the needle from surface of the water.

• Are you able to see the head of the needle?