What is scattering of light? Explain why the clear sky appears blue.

1. 1 · Define in one line. Scattering is the sending of light in all directions by tiny particles in its path.
2. 2 · Link particle size and colour. Very fine particles scatter mainly blue light (short wavelength). Large particles scatter all colours, so the light looks white.
3. 3 · Explain the blue sky. Air molecules are smaller than the wavelength of visible light, so they scatter blue light more strongly than red. This scattered blue light reaches our eyes from all over the sky.
4. 4 · Add what happens without air. With no atmosphere there would be no scattering, and the sky would look dark, as it does from very high altitudes.
5. 5 · Daily-life link. A sunbeam through a window in a dusty or incense-filled room shows scattering too: the Tyndall effect.
6. 6 · Close in one line. So the blue sky is sunlight scattered by the molecules of air.

Scoring tip: Use the word wavelength and say that blue has a shorter wavelength than red. Writing only that blue is scattered more may not get full marks.