Question
Light wave enters from medium $1$ to medium $2.$ Its velocity in $2^{nd}$ medium is double from $1^{st}$. For total internal reflection the angle of incidence must be greater than.......$^o$
✓
Answer
(a) $\frac{{{\mu _2}}}{{{\mu _1}}} = \frac{{{v_1}}}{{{v_2}}} = \frac{1}{2} \Rightarrow \frac{{{\mu _1}}}{{{\mu _2}}} = 2({\mu _1} > {\mu _2})$
For total internal reflection $_2{\mu _1} = \frac{1}{{\sin C}} \Rightarrow \frac{{{\mu _1}}}{{{\mu _2}}}$
$ = \frac{1}{{\sin C}} \Rightarrow 2 = \frac{1}{{\sin C}} \Rightarrow C = {30^o}$
So, for total (Internal reflection angle of incidence must be greater than $30°.$
For total internal reflection $_2{\mu _1} = \frac{1}{{\sin C}} \Rightarrow \frac{{{\mu _1}}}{{{\mu _2}}}$
$ = \frac{1}{{\sin C}} \Rightarrow 2 = \frac{1}{{\sin C}} \Rightarrow C = {30^o}$
So, for total (Internal reflection angle of incidence must be greater than $30°.$
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