Refraction Questions

• Can a fire have a shadow?
• Can air make shadows?
• Does an atom have a color?
• Does the back of a rainbow look the same as its front side?
• How can a clear object be transparent and visible at the same time?
• Is a quadruple rainbow possible?
• When does light travel in a straight line?
• Why can't flat lenses focus light?
• Why does a rainbow exist only in a narrow band?