Light Intesity/ Current Relationship

[ed84c]

Can anyone tell me the relationship (formulas?) between light intensity and current in a filament light bulb?

[5614]

relationship = more current = more light intensity (until a limit which is quite high, far higher than a normal household light, but super-super-hyper-mega bright spot lights begin to reach the limit!)

 

dunno bout formulae, however it will depend on the bulb itself, the resistance and other properties of the filament itself.

[ed84c]

yes i guessed that was the relationshipe :-S

[cyeokpeng]

Assuming if the tungsten filament has an ohmic property,

 

Power dissipated = I^2*R

where R= resistence of the filament.

 

So as current increses, the intensity also increases by the power square law.

[swansont]

Assuming if the tungsten filament has an ohmic property' date='

 

Power dissipated = I^2*R

where R= resistence of the filament.

 

So as current increses, the intensity also increases by the power square law.[/quote']

 

Yes, but generally the resistance of the filament is temperature-dependent, and it gets very hot. So the overall behavior is much more complicated.

[YT2095]

the only data I have is that a regular incandescent light bulb is only 2% efficient, put in 100w and you`ll get 2W of light, the rest is heat an magnetic forces.