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LIGHT & OPTICS · LAB 25
Rainbow formation
Follow sunlight as it refracts, disperses and reflects inside water droplets to form primary and secondary rainbows.
RAINBOW TYPEPRIMARY
Switch views and adjust the incident ray to see how the outgoing angle changes
SunlightInternal pathEmergent spectrum
Snell’s law
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9° separation
one reflection
WHAT TO NOTICE
One droplet, one colour
Each wavelength bends by a slightly different amount. A primary bow uses one internal reflection; a secondary uses two and reverses the colour order. Every observer receives light from a different set of droplets.
n₁ sin i = n₂ sin rDp = 180° + 2i − 4r
Educational geometric-optics approximation; the droplet diagram is magnified.