Blackbody radiation.

Blackbody radiation

• The body which absorbs all the radiation falling on it irrespective of frequencies is called a Blackbody.
• The most important part of a Blackbody are its properties.
• Blackbody radiates more radiation when it is hot than when it is cold.
• The spectrum of a Blackbody is given below

  

  Spectrum of Blackbody radiation.

• From the spectrum of Blackbody radiation the following observations are made:

1. With the increase in temperature Blackbody radiates more and more energy.
2. The spectral energy of a Blackbody depends only on temperature. This relation was given by Stefan and Boltzmann known as Stefan's Boltzmann law as
                E 𝛂 T⁴

                E = 𝝈T⁴

3. The spectral energy density increase with increase in frequency but for higher frequencies it decreases.

4. A relation between temperature and frequency of a Blackbody was given by Wein's law i.e

      λₘT=hc=2.898 × 10⁻³mK.

Questions on Blackbody radiation;

Q1) What do you mean by Blackbody radiation?

Ans) The body which absorbs all the radiation falling on it irrespective of frequencies is called a Blackbody radiation.

Q2) State Stefan's Boltzmann law?

Ans) The spectral energy of a Blackbody depends only on temperature. This relation was given by Stefan and Boltzmann known as Stefan's Boltzmann law as

                 E 𝛂 T⁴

                E = 𝝈T⁴

Q3) State Wein's law?

Ans) A relation between temperature and frequency of a Blackbody was given by Wein's law i.e

      λₘT=hc=2.898 × 10⁻³mK.

Q4) What observations are made from spectrum of Blackbody radiation?

Ans) From the spectrum of Blackbody radiation the following observations are made;

1. With the increase in temperature Blackbody radiates more and more energy.
2. The spectral energy of a Blackbody depends only on temperature. This relation was given by Stefan and Boltzmann known as Stefan's Boltzmann law as
                E 𝛂 T⁴

                E = 𝝈T⁴

3. The spectral energy density increase with increase in frequency but for higher frequencies it decreases.

4. A relation between temperature and frequency of a Blackbody was given by Wein's law i.e

      λₘT=hc=2.898 × 10⁻³mK.