what is the critical angle for light passing from(n=1.54) to (n=1.33)

Answer 1

Snell's law: N_i*sin(Theta_i)= N_t*sin(Theta_t)
but at critical angle Theta_t=90 so
SinTheta_c= N_t/N_i=1.33/1.54=0.864 or
Theta_critical=59.7 deg