What is the Temperature of a 60W Lamp Filament?

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Discussion Overview

The discussion revolves around determining the temperature of the filament of a 60-watt lamp, considering parameters such as filament area and absorptivity. The context is primarily homework-related, involving the application of the Stefan-Boltzmann law.

Discussion Character

  • Homework-related, Mathematical reasoning

Main Points Raised

  • One participant presents a calculation using the equation Q = εσAT^4 to find the filament temperature, arriving at approximately 4169.894 K.
  • Another participant comments that the initial answer has too many significant figures and notes a potential issue with the units for the Stefan-Boltzmann constant.
  • A third participant mentions that their question sheet states the correct answer is 3800 K, questioning the validity of the initial calculation.
  • A fourth participant confirms that they computed the same answer as the first participant.

Areas of Agreement / Disagreement

Participants express differing views on the correctness of the initial calculation, with some agreeing on the computed value while others reference a different expected answer from the question sheet. The discussion remains unresolved regarding the accuracy of the temperature calculation.

Contextual Notes

There are limitations regarding the assumptions made in the calculations, including the treatment of significant figures and the accuracy of the provided constants. The dependence on the specific definitions of absorptivity and area may also affect the results.

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Homework Statement



Determine the temperature of the filament of a 60watt lamp, if the filament has an area of 10mm^2 and an absorptivity of 0.35. Assume stefan-Boltzmann constant is 5.67*10^-8 W/(m.K^4).

Homework Equations





The Attempt at a Solution



The equation I have attempted with is

Q= εσAT^4

60= 0.35*(5.67*10^-8)*(0.00001m^2)*(T^4)

T^4= 60/(0.35* 5.67*10^-8* 0.00001)

then 4th root of answer = 4169.894

is this correct?
 
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Looks correct with the following comments:

Your answer has too many significant figures.
Your units for the Stefan-Boltzmann constant are wrong.
 
Thats what I have been given on my question sheet, also they just give numerical answers and on the sheet it says the correct answer is 3800K that is why i put it up to check??
 
I compute the same answer as you did.
 

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