Answer:
[tex]\theta_c = 36.78^o[/tex]
Explanation:
The relationship between the refractive index and the critical angle is given as follows:
[tex]\eta = \frac{1}{Sin\ \theta_c} \\\\Sin\ \theta_c = \frac{1}{\eta}\\\\\theta_c = Sin^{-1}(\frac{1}{\eta} )[/tex]
where,
η = refractive index = 1.67
θc = critical angle =?
Therefore,
[tex]\theta_c = Sin^{-1}(\frac{1}{1.67} )[/tex]
[tex]\theta_c = 36.78^o[/tex]
