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COMEDK · Physics · 26. Wave Optics

Plane polarised light is passed through an analyser and the intensity of emerging light is reduced by \(75 \%\). Optical vibrations make an angle \(\theta\) with the axis of analyser, then \(\theta\) is

  1. A \(60^{\circ}\)
  2. B \(45^{\circ}\)
  3. C \(30^{\circ}\)
  4. D \(58^{\circ}\)
Verified Solution

Answer & Solution

Correct Answer

(C) \(30^{\circ}\)

Step-by-step Solution

Detailed explanation

Let \(I_{0}\) be the intensity of light incident on polariser. On passing through polariser, it gets reduced to \(\frac{I_{0}}{2}\). So, according to law of Malus, \(I=\frac{I_{0}}{2} \cos ^{2} \theta\) Given, \(\quad I=\frac{75}{100} \times \frac{I_{0}}{2}=\frac{3 I_{0}}{8}\)…