Candle Power/wattage?

[YT2095]

I was bought a 1,000,000 candle power flashlight as an early valentines present.
I was wandering what percentage of the power output is actualy light?

I seem to rem that an ordinary incandescent bulb is only 2% efficient (a 100w bulb will give you 2 watts of light output).

LEDs are 5% IIRC

this is a 55w Halogen bulb and I`ve no idea what the efficiency is for that type.
I`de like to know how much of this 55W is actualy light power and not heat or EM.
so I can work out how many candles it takes per Watt.

anyone know?

[Radical Edward]

what is the solid angle in steradians that it emits at?

[YT2095]

I work it out to about 2 watts of light making 1w = 500,000 candles.
based ENTIRELY upon the assumption that a Halogen bulb is twice as efficient as an ordinary bulb but not quite as good as a semi conductor.
it`s little more than a guess though tbh.

edit: "what is the solid angle in steradians that it emits at? "
erm... what`s that when it`s at home? LOL, I`ve got no idea man.
all I know is that it`s a 55W halogen working off a 6v SLA battery.
the focus is a concave mirror 4inch diameter.

[5614]

power output depends soley on the bulb itself.... and the bubls energy efficiency rating.

[swansont]

This (http://www.wordiq.com/definition/Light_bulb#Efficiency) site gives some efficiencies. 2% for incandescents is pretty close. But LEDs aren't much more efficient, according to the list. Halogens are.

Halogens run hotter, which means they give a whiter spectrum - normal incandescents look yellow - and hotter means a larger fraction of the total energy is in the visible. Which also explains why lower power incandescents are less efficient; they should be a little cooler.

Another advantage of halogens is that they redeposit the tungsten on the filament, and the bulb lasts longer.

Note that the link I give is the ratio of visible to total radiated power - it ignores any inefficiency in generating the EM spectrum in the first place.