Radiation Problem: Find Surface Area of Light Bulb Filament

  • Thread starter Thread starter brilapwnzall
  • Start date Start date
  • Tags Tags
    Radiation
AI Thread Summary
To find the surface area of a light bulb filament radiating 59 watts at a temperature of 3.2*10^3°C with an emissivity of 0.38, the Stefan-Boltzmann equation is used. The temperature must be converted from Celsius to Kelvin for accurate calculations. The correct formula is ΔQ/ΔT = eσAT^4, where σ is the Stefan-Boltzmann constant. The initial calculation yielded an incorrect surface area due to not converting the temperature to Kelvin. Proper conversion and application of the formula will yield the correct surface area.
brilapwnzall
Messages
1
Reaction score
0

Homework Statement


The filament of a light bulb has a temperature of 3.2*10^3°C and radiates 59 watts of power. The emissivity of the filament is 0.38. Find the surface area of the filament.

Homework Equations



\DeltaQ/\DeltaT=e\sigmaAT^4

\sigma=5.67*10^-8

The Attempt at a Solution



59=(.38)(5.67*10^-8)(A)(3.2*10^3)^4

Use needed Algebra to solve for A and I get 2.61e-5, but it's not the right answer.
Can someone please tell me what I am doing wrong?
 
Physics news on Phys.org
Your temperature 3.2*10^3°C is in Celsius, you need to convert it to Kelvin (K).
 
What temperature scale is implied by the Stefan-Boltzmann constant?
 

Thread 'Errors and significant figures'

I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
View full post »
Thread 'A cylinder connected to a hanging mass'

Thread 'A cylinder connected to a hanging mass'

Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
View full post »

Similar threads

Power Radiated From a Copper Cube
Replies
3
Views
796
Solving 100W Lightbulb Filament Surface Area Problem
Replies
3
Views
3K
What is the surface area of the filament? heat expansion and transfer
Replies
12
Views
8K
Thermal radiation lab experiment
Replies
5
Views
4K
Light bulb & Diode: linear or non-linear elements.
Replies
12
Views
9K
Radiation Rate of 0.1m Cube Metal at 200C
Replies
3
Views
975
Problem involving thermal radiation and specific heat
Replies
11
Views
4K
Average Pressure Radiation on Perfectly Absorbing Surface
Replies
6
Views
3K
Photon Arrival Rate, Chapter 1.5 from Computer Graphics by Folly
Replies
15
Views
2K
Tungsten filament-finding length of coil
Replies
1
Views
6K

Hot Threads

Recent Insights

Back
Top