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MHT CET · Physics · Ray Optics

A ray of light travelling through a rarer medium is incident at very small angle ' \(i\) ' on a glass slab and after refraction its velocity is reduced by \(25 \%\). The angle of deviation is

  1. A \(\frac{3 \mathrm{i}}{4}\)
  2. B \(\frac{\mathrm{i}}{4}\)
  3. C \(\frac{\mathrm{i}}{3}\)
  4. D \(\frac{4 \mathrm{i}}{3}\).
Verified Solution

Answer & Solution

Correct Answer

(B) \(\frac{\mathrm{i}}{4}\)

Step-by-step Solution

Detailed explanation

\(n=\frac{\sin i}{\sin r}=\frac{i}{r} \quad\) \(\ldots(\because i \text { is very small, } \sin i \approx i)\)
\(n=\frac{c}{v}=\frac{c}{0.75 c}=\frac{i}{r}\)
\(\therefore r =0.75 i=\frac{3}{4} i\)
\(\delta=i-r=i-\frac{3}{4} i=\frac{i}{4}\)