question_answer

(a) A plane wavetront approaches a plane surface separating two media. If medium one is (optically) denser and medium two is (optically) rarer, construct the refracted wave front using Huygens' principle. Hence prove Snell?s law. (b) Draw the shape of the refracted/reflected wavefront when a plane wavefront is incident on (i) prism and (ii) convex mirror. Give a brief explanation for the construction.                          

Answer:

                (a) The refracted wavefront CE is shown in Fig. \[\sin i=\frac{BC}{AC}=\frac{{{\upsilon }_{1}}t}{AC}\] \[\sin r=\frac{AE}{AC}=\frac{{{\upsilon }_{2}}t}{AC}\] \[\therefore \]  \[\frac{\sin i}{\sin r}=\frac{{{\upsilon }_{1}}}{{{\upsilon }_{2}}}\] or \[^{1}{{\mu }_{2}}=\frac{{{\upsilon }_{1}}}{{{\upsilon }_{2}}}=\]a constant This prove Snell?s law of refraction. (b) Explanation. The time taken by any disturbance to travel from incident wave front to the refracted or reflected wave front is same.