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Black Body Radiation: Determination of Stefan's Constant
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Procedure for performing real lab:

 

  1. Remove the disc from the bottom of the hemisphere and switch on the heater and allow the water to flow through it.
  2. Allow the hemisphere to reach the steady state and note down the temperature T1, T2, T3 .
  3. Fit the disc (black body) at the bottom of the hemisphere and note down its rise in temperature with respect to time till steady state is reached.
  4. A graph is plotted with temperature of disc along Y-axis and time along X-axis as shown.
  5. Find out the slope dT/dt from the graph.

                        

 

 

 

 

 

 

 

Procedure for performing simulator:

 

 

 

 

  1. Choose desirable values of water temperature, surrounding temperature, mass and radius of the disc using the sliders.
  2. Click the "Power ON" button and wait till T1, T2 ,T3 reach steady state. Note down its values.
  3. Putting T4 button, click "Fit the disc'' option.
  4. Note down T4 at different intervals of time till it reaches steady state.
  5. Plot Temperature-Time graph and determine its slope .
  6. Determine Stefan's constant '«math xmlns=¨http://www.w3.org/1998/Math/MathML¨»«mi»§#963;«/mi»«/math»' using the given formula.

 

Observations:


 

 

Calculations:

 

Mass of the copper disc  =  ...... kg

Specific heat of copper  =  ...... Jkg-1

Radius of the disc  = ..... m

Area of the disc = ......m2
Slope of the graph   = ……Ks-1
 

 

Substituting the values in the given expression,

«math xmlns=¨http://www.w3.org/1998/Math/MathML¨»«mi»§#963;«/mi»«mo»=«/mo»«mfrac»«mrow»«mi»m«/mi»«msub»«mi»C«/mi»«mi»p«/mi»«/msub»«mo»§nbsp;«/mo»«mfrac»«mrow»«mi»d«/mi»«mi»T«/mi»«/mrow»«mrow»«mi»d«/mi»«mi»t«/mi»«/mrow»«/mfrac»«/mrow»«mrow»«mi»A«/mi»«mfenced»«mrow»«msup»«msub»«mi»T«/mi»«mi»h«/mi»«/msub»«mn»4«/mn»«/msup»«mo»-«/mo»«msup»«msub»«mi»T«/mi»«mi»d«/mi»«/msub»«mn»4«/mn»«/msup»«/mrow»«/mfenced»«/mrow»«/mfrac»«/math»= …………………………… Wm-2K-4
 

 

Result:

 

Stefan-Boltzmann’s constant    σ  =……………. Wm-2K-4
 

 

 

Cite this Simulator:

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