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Homework Help: Pressure of a lightbulb

  1. Sep 7, 2015 #1
    1. The problem statement, all variables and given/known data

    Suppose a gas-filled incandescent light bulb is manufactured so that the gas inside the bulb is at atmospheric pressure when the bulb has a temperature of 20.0 °C. Find the gauge pressure inside such a bulb when it is hot, assuming its average hot temperature is 65.0 °C.

    2. Relevant equations

    (p/t)=(p'/t') where the left hand side is initial pressure and temperature, the right is the when hot.

    t= 293.15 K
    t'=338.15 K

    the gas inside is at atmospheric pressure.

    3. The attempt at a solution

    1atm= 1.013x^5 Pa

    i use the formula above, and solve for p'

    p' = (pt')/t

    p'=(1.013x10^5)(338.15)/(293.15) (Pa*K)/(K) (the right stuff are the units of measurement used)

    116850.0597 Pa.

    However, I am not getting the answer. I never took a chemistry class, so I am unsure what the difference between gauge pressure/ atmospheric/ absolute pressure is and how to convert it.

    I believe my formula is correct but I am not using the correct pressure values.
  2. jcsd
  3. Sep 7, 2015 #2
    Google "gauge pressure."

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