Ray Optics and Optical Instruments - Result Question 60

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63. A thin prism of angle $15^{\circ}$ made of glass of refractive index $\mu_1=1.5$ is combined with another prism of glass of refractive index $\mu_2=1.75$. The combination of the prism produces dispersion without deviation. The angle of the second prism should be

======= ####63. A thin prism of angle $15^{\circ}$ made of glass of refractive index $\mu_1=1.5$ is combined with another prism of glass of refractive index $\mu_2=1.75$. The combination of the prism produces dispersion without deviation. The angle of the second prism should be

3e0f7ab6f6a50373c3f2dbda6ca2533482a77bed:content/english/neet-pyq-chapterwise/physics/ray-optics-and-optical-instruments/ray-optics-and-optical-instruments—result-question-60.md (a) $7^{\circ}$

(b) $10^{\circ}$

(c) $12^{\circ}$

(d) $5^{\circ}$

[2011M]

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Answer:

Correct Answer: 63. (b)

Solution:

  1. (b) Deviation $=$ zero

So, $\delta=\delta_1+\delta_2=0$

$\Rightarrow(\mu_1-1) A_1+(\mu_2-1) A_2=0$

$\Rightarrow A_2(1.75-1)=-(1.5-1) 15^{\circ}$

$\Rightarrow A_2=-\frac{0.5}{0.75} \times 15^{\circ}$

or $A_2=-10^{\circ}$.

Negative sign shows that the second prism is inverted with respect to the first.