Bent Twice, Seen Once: teacher key

Rainbows, grade 8 edition, written for 8th grade. Raindrops are not tiny prisms, yet they split sunlight into a bow. Follow the bending, the bouncing and the angles that put each color in its place.

Read the book. Print this page for the key.

Questions and answers

1. Why do raindrops split sunlight into colors?
   • Each drop is a tiny prism
   • The light is bent twice at the curved surfaces of a nearly round drop (answer)
   • The drops are colored
2. Where does most of the light leaving a raindrop concentrate?
   • Near 12 degrees
   • Near 90 degrees
   • Near 42 degrees (answer)
3. Two friends stand side by side watching a rainbow. What is true?
   • They see exactly the same drops
   • A different set of raindrops makes the rainbow each one sees (answer)
   • Neither can see it
4. What does 'diffracts' mean in the fogbow page?
   • Spreads out (answer)
   • Freezes
   • Reflects twice
5. Why does a rainbow near sunset sometimes look red?
   • Rain turns red at night
   • The long path through air removes blue and green light (answer)
   • Violet bends the most

Words

• indigo: deep blue-violet
• spectrum: band of colors
• wavelength: wave length
• diffracts: spreads out
• antisolar: opposite the sun