1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

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.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook