Ray Optics And Optical Instruments Ques 53
53. A thin prism having refracting angle $10^{\circ}$ is made of glass of refractive index 1.42. This prism is combined with another thin prism of glass of refractive index 1.7. This combination produces dispersion without deviation. The refracting angle of second prism should be
[2017]
(a) $6^{\circ}$
(b) $8^{\circ}$
(c) $10^{\circ}$
(d) $4^{\circ}$
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Answer:
Correct Answer: 53.(a)
Solution:
- (a) For dispersion without deviation
$(\mu-1) A_1+(\mu^{\prime}-1) A_2=0$
$|(\mu-1) A_1|=|(\mu^{\prime}-1) A_2|$
$(1.42-1) \times 10^{\circ}=(1.7-1) A_2$
$4.2=0.7 A_2$
$A_2=6^{\circ}$
In case of deviation without dispersion
$ \frac{A^{\prime}}{A^{\prime}}=\frac{(\mu_V-\mu_R)}{(\mu_V^{\prime}-\mu_R^{\prime})} $
BETA
