Chapter 15, Problem 23A

To determine

The way, the speed of light will appear near an observer standing at rest outside of the train

Explanation of Solution

Introduction:

From one of the postulates of special theory of relativity, the speed of light in free space is same for every inertial frame. Depending on the relative velocity of the observer and the light source, the speed of light does not change, in other words speed of light is constant in each reference frame.

As per this postulate, if light is shined in the direction of the motion of train or light be shined in the opposite direction of the motion of train, in both of the cases speed of light will appear near the rest observer same as its original value, that is $3\times {10}^8$ m/s, that is same as it appears near the observer on the train.