[Phys-l] 50 year incandescent bulb

[Chuck Britton <britton@ncssm.edu>]

At 10:21 AM -0700 on 5/1/07, Jason Alferness wrote
> But then, I'm still a little confused why they can't design a 50 year
> incandescent bulb...


My (limited) understanding is that a 50 incandescent bulb could be 
designed - but it would not give off as much light as you would 
expect.

I notice that (some?) 'long life' incandescent bulbs are 'rated' at 
130 volts rather than the more common 120 volts.

I.e. the filament is cooler when it is used at 120 volts and is 
putting out less than the rated wattage (wattage rated at 130 volts 
=> longer life due to 120 volt use)