Uncovering the Source of Extra 267 J in Standard Incandescent Light Bulb

[Drakkith]

I see. So then if you want to dissipate 100 watts you have to balance length and thickness to get the resistance at the right amount and also keep the temperature from either being too low (which will make a dim, inefficient bulb) or too high (reducing filament life).

Also, do you know if my assumption is post #13 about using less surface area in the calculation is accurate at all?

 

[Vanadium 50]

I said heat, not temperature. The thing that destroys bulbs is heat.

I am not sure how important the shadowing effect is. If you model a coil as a hollow tube, the light's dependence on the inner radius is only through the thickness of the tube and thus its resistivity.

 

[Drakkith]

I said heat, not temperature. The thing that destroys bulbs is heat.

I don't know what you mean by this. Could you elaborate?

 

[Paul Colby]

I don't have a reference but I recall coiling a filament reduces failure due to thermal shock. Time lapse movies of lights turning on show considerable vibration due to sudden temperature changes.

 

[Vanadium 50]

I don't know what you mean by this. Could you elaborate?

Heat and temperature are two different quantities - I can stick my hand in a 350 degree oven without injury, but I can't stick it in a 212 degree pot of boiling water. I wrote heat because I meant heat. That's all I meant.