Statement Plotting the graph Calculating value of $(\mu)$ refractive index (i) When the pass axis of a polaroid makes an angle $heta$ with the plane of polarisation of polarised light of intensity $I_0$ incident on it, then the intensity of the transmitted emergent light is given by $I=I_0$ $\cos^2 heta$ Note : If the student writes the formula $I=I_0 \cos^2 heta$ and draws the diagram give 1 mark (ii) (iii) $\; \mu = \tan i_{\beta}$$\; = an 60^{\circ} = \sqrt{3} = 1.7$