11. Differentiate between refraction of light and dispersion of light.

Refraction refers to any bending of waves due to a change in speed. In the case of light being refracted by a prism, dispersion means that the higher the frequency light bends more. In short, Refraction is the bending of light and Dispersion is the frequency dependece of this behaviour.

r=rho l/a where a is the area, l is the length and rho is resistivity so the greater the area the lesser the resistance thats why the earth pin is thicker bcos current follow the shortest path, so less resistive .

double the distance = divide strength by 4