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A ray PQ is incident normally on the face AB of a triangular prism of refracting angle 60°, made of a transparent material of refractive index 2/sqrt(3) , as shown in Fig. Trace the path of the ray as it passes through the prism. Also calculate the angle of emergence and angle of deviation. |
Answer» Solution :A TRACE of PATH of the ray through the prism is shown in Fig. 9.80. Here at first face AB of the prism `anglei =0` and hence, `angler_(1) =0^(@)` too. At the second face AC, the ray subtends an angle `angler_(2) = angleA - angler_(1) = 60^(@) - 0^(@) = 60^(@)`  As refractive index of prism `n=2/sqrt(3)`hence critical angle for prism-air interface is: `i_( c) = sin^(-1)(1/n) = sin^(-1)(sqrt(3/2)=60^(@)` Thus, while UNDERGOING refraction at second face of prism, the emergent ray RS travels just along the face AC so that angle of emergence `anglee = 90^(@)` . Moreover angle of deviation `delta =angle(TRS) = 30^(@)` |
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