Question

Use the formula lm T = 0.29 cmK to obtain the characteristic temperature ranges for different parts of the electromagnetic spectrum. What do the numbers that you obtain tell you?

Answer 1

In case of Black Body Radiation , the wavelength corresponding to maximum Intensity is given by by Planck’s Law.

λm=0.29 cm k / T

where λm = maximum wavelength

T= temperature  

The temperature for different wavelengths can be obtained as :

• For λm= 10⁻⁴cm

T= 0.29/10⁻⁴ = 2900 K

• For λm= 5 x 10 ⁻⁵cm

T=0.29/ 5x 10⁻⁵ = 5800 K

• For λm= 10⁻⁶cm  

T= 0.29/10⁻⁶    =290000 K

And so on

The numbers that we have obtained above tells us that :

• As wavelength increases , corresponding temperature increases

• Temperature ranges are required for obtaining  radiations in different parts of electromagnetic spectrum