question_answer

In vacuum, to travel distance d, light takes time t and in medium to travel 5d, it takes time T. The critical angle of the medium is:

A) \[{{\sin }^{-1}}\,\left( \frac{5T}{t} \right)\]                     

B) \[{{\sin }^{-1}}\,\left( \frac{5t}{3T} \right)\]

C) \[{{\sin }^{-1}}\,\left( \frac{5t}{T} \right)\]                     

D) \[{{\sin }^{-1}}\,\left( \frac{3t}{5T} \right)\]

Correct Answer: C

Solution :

[c]   \[{{R}_{net}}=40.8+\frac{20\times 480}{20+480}\] \[40.8+19.2=60\Omega \] \[I=\frac{V}{{{R}_{net}}}=\frac{30}{60}\] \[I=0.5A\]