Light travels through air at $3.0 \times 10^{8}\,\text{m s}^{-1}$. For a transparent plastic material in air, the critical angle for light is $37^{\circ}$. What is the speed of light in the plastic material?
- A$1.8 \times 10^{8}\,\text{m s}^{-1}$
- B$2.4 \times 10^{8}\,\text{m s}^{-1}$
- C$3.8 \times 10^{8}\,\text{m s}^{-1}$
- D$5.0 \times 10^{8}\,\text{m s}^{-1}$