# Fundamental Physics/Light

(Redirected from Light)

## Light

Light comes from light sources for example Sun, Star,Moon, Electric lamp, Gasoline lamp, Fire, Candle, Fire fly

## Light interaction

Visible light interacts with matter creates

• Heat transfer . Energy absorbs by matter from interaction with light's energy depend on matter's thickness and its color . Observation shows that dark and thin clothes dry faster than bright and thick clothes
• Color lights . Rainbow of 7 colors

## Visible light

James clerk Maxwell has shown that Visible light travels as Electromagnetic wave of a constant speed in vacuum and in air with a visible wave length 400-700 nm

Speed of visible light

${\displaystyle v=C=\omega _{o}=\lambda _{o}f_{o}={\sqrt {\frac {1}{\mu _{o}\epsilon _{o}}}}=3\times 10^{6}m/s}$

Wave length of a visible light

${\displaystyle \lambda _{o}=400-700nm}$

According to Planck, all matter radiates visible light at Threshold frequency, fo . Hence,

${\displaystyle f_{o}={\frac {C}{\lambda _{o}}}}$
${\displaystyle f_{o}={\frac {3\times 10^{6}m/s}{400-700nm}}}$

Energy of visible light

${\displaystyle E=pv=pC=p\lambda _{o}f_{o}=hf_{o}}$

With

${\displaystyle h=p\lambda _{o}}$

## Visible color lights

Experiment has shown that visible light decompose into its composite color lights when light travels through prism . There are 6 colors are observed namely Red, Orange, Yellow, Green, Blue, Violet

 Color Angle of fraction Wavelength Red Orange Yellow Green Blue Violet