# Perspex is a form of transparent plastic where a ray of light strikes the flat surface of the block with an angle of 40 degrees along the normal. What would be the angle of refraction if the refractive index of the material is 1.5

According to the question, it says the ray of light makes an angle of $40^0$  along the normal. Therefore we can say that the angle of incidence of the light is $40^0$.

Using Snell's Law, we get

$\begin{array}{l} \Longrightarrow \mu=\frac{\sin 40^{\circ}}{\sin r} \\ \\ \Longrightarrow 1.5=\frac{0.64}{\sin r} \\\\ \Longrightarrow \sin r=\frac{0.64}{1.5} \\\\ \Longrightarrow \sin r=0.426 \end{array}$

So

\begin{aligned} &\Longrightarrow \text { Angle of Refraction }=\sin ^{-1}(0.426)\\ &\Longrightarrow \text { Angle of Refraction }=25.21^{\circ} \end{aligned}

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