Q10 of 29 Page 109

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)

When the bright metal ball is made black with soot in candle flame the air enters the space between the soot and metal ball.

• Light passes from the denser medium (water) to the rarer medium (air).


• When the angle of incidence exceeds the critical angle, the total internal reflection takes place.



• The ball appears to be shining due to total internal reflection.


More from this chapter

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8

Explain the phenomenon of total internal reflection with one or two activities. (AS1)

 9

How do you verify experimentally that the angle of refraction is more than angle of incidence when light rays travel from denser to rarer medium. (AS1)

 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)

 12

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