Features (observations) of the curves shown
- The curves at lower temperatures lie completely inside those at higher temperatures,
- The intensity for each wavelength increases with increase in wavelength but the increase is faster on the side of the shorter wavelength,
- At each temperature T, the energy emitted is maximum for a certain wave length which decreases with rising temperature.
NOTE: The dotted line shows the locus of the peaks of the curves for the different temperatures.
Conclusions from the above observations
- A body radiates energy at a rate which is determined by the nature of the surface and its temperature,
- A body absorbs energy at a rate determined by the nature of the surface and the temperature of the surroundings,
- The area under any particular curve is the total energy radiated per unit surface area per second; at the corresponding temperature.
