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Standard XII

Physics

Lateral Displacement

A light ray i...

Question

A light ray is travelling from Region $1$ to $4$ as shown in the figure. The refractive index of the regions are also mentioned there. The angle of incidence $θ$ for which the beam just missess entering region $4$ is :

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Solution

As per the question, the ray will graze at the boundary of Region $4$ . To satisfy this condition incident ray will fall at critical angle on the interface between medium $3$ and $4$ .

Therefore, from Snell's law we have:
$n_{0} sin θ = \frac{n_{0}}{8} sin 90^{\circ}$
$\Rightarrow θ = {sin}^{- 1} (\frac{1}{8})$

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A light ray is travelling from Region 1 to 4 as shown in the figure. The refractive index of the regions are also mentioned there. The angle of incidence θ for which the beam just missess entering region 4 is :

As per the question, the ray will graze at the boundary of Region 4. To satisfy this condition incident ray will fall at critical angle on the interface between medium 3 and 4. Therefore, from Snell's law we have: n0sinθ=n08sin90∘ ⇒θ=sin−1(18)

A light ray is travelling from Region $1$ to $4$ as shown in the figure. The refractive index of the regions are also mentioned there. The angle of incidence $θ$ for which the beam just missess entering region $4$ is :