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InterviewSolution
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The diagram below shows a glass block suspended in a liquid. A beam of light of single colour is incident from liquid on one side of the block. (a) Draw diagrams to show how does the light bend when it travels from liquid to glass and then to liquid if (i) the light slows down in glass, and (ii) the light speeds up in glass. (b) State two conditions under which the light ray passing from liquid to glass travels straight without bending. will the glass be visible then ? |
Answer» Solution :(a) (i) If light shows down in going from liquid to glass, it means that `mu_(glass) gt mu_(liquid)`, so it will BEND towards the normal at the POINT of incidence in passing from liquid to glass at the first surface, while it will bend away from the normal at the SECOND surface in passing from glass to liquid. the ray diagram is shown in figure. the light beam suffers lateral displacement.  (ii) If light speeds up in going from liquid to glass, it means that `mu_(glass) lt mu_(liquid)`, so it will bend away from the normal at the point of incidence on the first surface in passing from liquid to glass, while it will bend towards the normal at the second surface in passing from glass to liquid. the ray diagram is shown in figure. the light beam sufers lateral displacement in a direction opposite to that in case (i).  (b) A light ray passing from liquid to glass travels straight WITHOUT bending under the following two conditions: (1) when the light ray falls normally on glass from liquid (i.e., if `anglei=0^(@),angler=0^(@)`) (2) When refractive index of liquid is same as that of glass (or speed of light in glass is same as in liquid). In both the above conditions, the glass BLOCK will not be visible inside the liquid. |
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