Question

A thin glass prism has refractive index \(1.5\). The correct relation between the angle of minimum deviation \((δm)\) and angle of refraction \((r)\) is

• A. \(δm = \frac{r}{2}\)
• B. \(δm = 2r\)
• C. \(δm = r\)
• D. \(δm = \frac{3r}{2}\)

Hint:

For a thin prism the deviation is (mu - 1) A, and at minimum deviation r equals A over 2.

Answer 1

The Correct Option is C

Step 1: Approach
Use the prism formula in terms of $r$.

Step 2: Relation
$r_1=r_2=r=\dfrac A2$, so $A=2r$. Then $\delta_m=(\mu-1)A=(0.5)(2r)=r$.

Step 3: Answer
Option (C).

Final Answer:
With index 1.5 the deviation is A over 2, which equals the angle of refraction r, option (C). \[ \boxed{\delta_m=r} \]