Q12 of 29 Page 109

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

1. Take the cylindrical transparent vessel and put the coin at the bottom of the vessel.

2. Now pour some water in vessel until we get some image of coin on the water surface.


3. The coin is visible only when we pour the water into the vessel. This is because of total internal reflection. The figure below depicts the same.



We know that



⇒


∵ refractive index of water is 1.33.


⇒ c =


c = 48.7o.


Hence critical angle of water is 48.7o.


More from this chapter

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10

Take a blight metal ball and make it black with soot in a candle flame. Immerse it in water. How does it appear and why? (Make hypothesis mid do the above experiment). (A52)

 11

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)

 13

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

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

 14

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