Arrange the following media according to velocity of a laser beam in them in ascending order.
A. Flint glass
B. Diamond
C. Water
D. Air
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → B, A, C, D
The speed of light in a medium is \( v = c/n \), so the medium with the larger refractive index has the smaller speed.
\( \text{(B) Diamond: } n \approx 2.42,\ v \approx 1.24\times10^{8}\,\mathrm{m\,s^{-1}} \)
\( \text{(A) Flint glass: } n \approx 1.65,\ v \approx 1.82\times10^{8}\,\mathrm{m\,s^{-1}} \)
\( \text{(C) Water: } n \approx 1.33,\ v \approx 2.26\times10^{8}\,\mathrm{m\,s^{-1}} \)
\( \text{(D) Air: } n \approx 1.0003,\ v \approx 3.0\times10^{8}\,\mathrm{m\,s^{-1}} \)
The ascending order of speed is B, A, C, D.