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Homework Help: Boltzman Constant, Emissivity and Surface Area of a filament

  1. Jan 21, 2010 #1
    1. The problem statement, all variables and given/known data

    A tungsten filament in a lamp is heated to a temperature of 2.30 x 10^3 K by an electric current. The tungsten has an emissivity of 0.31. What is the surface area of the filament if the lamp delivers 35.0 W of power?

    2. Relevant equations Stefan's Law

    (a greek letter that looks like P?) P(net)=ekAT^4

    3. The attempt at a solution

    35.0=0.31(5.670x10^-8 w/m^2*K^4)(2.30*10^3)^4A

    35.0 = 491876.5257A

    35.0/491876.5257=A

    7.1156069x10^-5


    is this correct?

    Thanks in advance for your help.
     
  2. jcsd
  3. Jan 22, 2010 #2
    Problem solved! Thank you.
     
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