In a way, it is kind of a trick question, because the most common answer (300,000 km/s) assumes that the phrase “in a vacuum” accompanies the question. The reason prisms diffract light into different colors is because some of the light waves go more slowly thru a solid medium than thru empty space.
In a way, it is kind of a trick question, because the most common answer (300,000 km/s) assumes that the phrase “in a vacuum” accompanies the question. The reason prisms diffract light into different colors is because some of the light waves go more slowly thru a solid medium than thru empty space.