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The amount of heat energy radiated by a metal at temperature 'T' is 'E'. When the temperature is increased to 3T, energy radiated is

The amount of heat energy radiated by a metal at temperature 'T' is 'E'. When the temperature is increased to 3T, energy radiated is Correct Answer 81 E

CONCEPT:

  • In the world, all objects emit radiation if they have a temperature greater than absolute zero ( 0K ).
  • And this radiation energy (Q) is proportional to fourth the power of Temperature (T) in Kelvin.
    • i.e. Q α T4 or mathematically  Q = σAT4

where σ is Stefan-Boltzmann constant and A is the area from which radiation is emitted. 

CALCULATION:

given that:

The temperature of the metal is tripled; T2 = 3T

Initially, Heat released by the metal Q1 = σAT4

Later, Heat released by the metal Q2 = σAT4

As the temperature is tripled, T2 = 3T

So Q2 = σAT24 = σA(3T)4 = 81 σAT4

Q2 = 81 Q1

  • So, the correct answer is option 4.

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  • An object that absorbs and emits all possible radiation with 100% is called a blackbody.

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