Determination of Stefan's constant

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Aim:- 

To determine the value of Stefan's constant.


Apparatus:- 

Black body radiation unit, Ammeter, Voltmeter, connecting wires, DC source.

Theory:- 

Stefan's constant: A physical constant denoted by σ, is the constant of proportionality in the Stefan's-Boltzmann law- the total intensity radiated over all wavelength increases as the temperature increases

Procedure:-

1) The electrical connections are made as shown in the circuit diagram.
2) Copper black body radiator is preheated to 300C  by setting maximum voltage in the power supply
3)after the temperature indicator indicates a temperature of about  300C, the voltage is reduced to some value 
4) increase the voltage in steps of 0.2 V and note down the current, hence calculate power l.
5) Determine the value of Stefan's constant.

Observations:- 

Room temperature
to=t+273=......of
2) surface area of the black body
 A=4πr2  =.........m square

Calculation σ = P/AT4

Results:-

1)Stefan's constant standard value σ =5.67×10-8 w/m2/k4

2) Stefan's constant experimental value  σ=.......w/m2/k4






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