Refraction and Reflection in a drop

• since water is more dense than air, light is refracted as it enters the drop- red is bent less, blue more
• some of the light will reflect off the back of the drop if the angle is larger than the critical angle (48° for water)
• the light is then refracted again as it leaves the drop, the colors of white light have been dispersed.
  • blue light will leave the drop at an angle of 40° from the beam of sunlight
  • red light will leave the drop at an angle of 42° from the beam of sunlight
• this process generates the primary rainbow ->

• However, you can not see the blue light and red light refracted from the same drop!!
• So, many drops are involved in producing the rainbow....