Understanding Formation of a Rainbow

1. Understanding Formation of a Rainbow By Tin Wei Heng

2. Contents • Rationale • Colours of a rainbow • Introduction to light dispersion • Refraction and reflection of light in water droplet • Maximum angle at which light should leave droplet to see rainbow • Rainbow as a 3D cone

3. Rationale • Understand the formation of rainbow • Understand how light disperses better • Better understand the reflection and refraction of light

4. Colours of Rainbow • Red • Orange • Yellow • Green • Blue • Indigo • Violet • The colours of the Rainbow are also known as the colours of light when it is dispersed

5. Dispersion of light • Dispersion of light occurs when light passes through from one medium to another • This causes different colours to refract at different angles • This phenomenon splits white light into the colours of a rainbow

6. Refraction and reflection of light in a water droplet • Light is first refracted entering the surface of the raindrop,reflected off the back of the drop, and again refracted as it leaves the drop

7. Angle • The most intense light can only leave the droplet at an angle of 42 degrees to see the rainbow • This is because if the sun is higher than 42 degrees, the rainbow will then be below the horizon and usually cannot be seen • This is because there are not usually sufficient raindrops between the horizon(eye level) and the ground • Exceptions occur when the observer is high above the ground E.g. Ferris wheel, aeroplane

8. Formation of a Rainbow(Complete) • Light first enters the droplet at an angle of 42 degrees or less • It is then refracted when entering the surface of the droplet • The light is then dispersed into different colours(colours of the rainbow) • Light is then reflected off the back of the raindrop and again refracted as it leaves the drop

9. After all this hard work you get…….. • TADA!!!!!!

10. Thank You