For a prism of prism angle $\theta =60°$, the refractive indices of the left half and the right half are, respectively, $n_1$ and $n_2$, $\left(n_2\ge n_1\right)$ as shown in the figure. The angle of incidence $i$ is chosen such that the incident light rays will have minimum deviation if $n_1=n_2=n=1.5.$ For the case of unequal refractive indices, $n_1=n$ and $n_2=n+∆n$ (where $∆n<<n$), the angle of emergence $e=i+∆e$. Which of the following statement(s) is(are) correct?

• A

  The value of $∆e$ (in radians) is greater than that of $∆n$.
• Correct answer
  B

  $∆e$ is proportional to $∆n$.
• Correct answer
  C

  $∆e$ lies between $2.0$ and $3.0$ milliradian, if $∆n=2.8\times {10}^{-3}$.
• D

  $∆e$ lies between $1.0$ and $1.6$ milliradians, if $∆n=2.8\times {10}^{-3}$

Hence, the correct answer is options: 'B', 'C'.