h by black body radiation

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Aim:- 

To determine Planks constant by black body radiation method 


 
Apparatus:-

Ammeter, Voltmeter, Black body radiator, connecting wires.


Theory:- 

As per planks, quantum theory energy is radiated in packets of energy called quanta, each quantum has the energy of hϑ where h is Plank's constant  (h=6.625×10-34  Js)


Procedure:-

1)The electrical connections  made as shown in the circuit diagram.
2) The 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 the power.
5)Hence calculate Stefan's constant and thereby Planks constant.



Observations:-

1) Boltzmann constant k=1.38×10-23J/K
2) Velocity of light c=3×10-8 m/sec

 Calculation:-

h=∛2 π5k4/15σc2


Result:-
 *Standard value of h=6.625×10-34 Js
*Determined value of h=




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