A prism is used for refracting light.
Refraction is the bending of light cause by a speed change when it passes through different media.
The speed of light changes when it passes from air into a prism.
What aspect of light changes when it passes from air into a prism?
Options:
  * power
  * seasons
  * speed
  * energy
  * a wave
  * Joules
  * heat
  * unique