A beam of light in air is incident on the surface of a rectangular block of clear plastic (n = 1.49).If the velocity of the beam before it enters the plastic is 3.00 × 10⁸ m/s,what is its velocity inside the block? A)3.00E+8 m/s B)1.35E+8 m/s C)2.01E+8 m/s D)2.46E+8 m/s E)1.53E+8 m/s

Question

Quizplus · Accepted Answer

The velocity of light in a medium is given by $v = \frac{c}{n}$, where $c$ is the speed of light in vacuum (3.00 × 10^8 m/s) and $n$ is the refractive index of the medium. For the plastic block with $n = 1.49$, the velocity of light inside the block is $v = \frac{3.00 × 10^8 m/s}{1.49} = 2.01 × 10^8 m/s$.

A Beam of Light in Air Is Incident on the Surface