firefire

Thanks very much for the response swansont

I think I might use the sun later in the year!

You need a power meter to measure the actual power.

 

If you have an incandescent source, thermodynamics tells us that your target will never get hotter than the source. The ability to focus is not a simple analysis for a wide-spectrum source. If it's not a thermal source, I'm not sure what the proper measurement is — you need a conversion from the power density to the effective temperature.

Thanks very much externet,

The reason I ask how I can estimate the type of light that might work easily is because I would like to use the most mundane light possible. It seems a laser may be mundane for you

Thanks

Sorry I'm a little confused how do I measure the 'power'?

Lets reverse it, say for example

- i have a halogen table lamp, 20w.

- I am using lenses made of clear ice or water in a plastic bag to focus the light.

If there a way to measure how much I can focus the light with these lenses and therefore how much power is required?

Thanks for your your response.

Right. A narrow spectrum and small source size will help reduce the total power needed. A big lens captures more light, but the quality of your optics matters too.

 

 

It's the total power. (It's not the luminous flux, measured in lumens, which is a value adjusted for the eye's sensitivity)

Thanks StringJunky, Natural tinder is a wonderful thing! King alfred cakes have to be my favorite. http://www.mushroomdiary.co.uk/2010/06/cramp-balls/ they have a good glow.

The thin silvery outer skin of the Silver Birch tree is very flammable if you have them around...just peel some slivers off.

Thanks swansont,

So just to clarify,

I am looking for a spot light with a narrow spectrum and big magnifying glass to focus the light, it should be possible.

Are their some light bulbs that emit more 'light' that would aid me? How is that measured?

Thanks

I think it's more the ability to focus the light. I've burned myself with less than 1 Watt of visible light, but it was from a laser and focused down to a few microns. Light from an extended source, with a wider spectrum isn't going to be prone to being focused down to such a small spot — different wavelengths will focus at different distances.

 

IR isn't heat. What matters more is the ability of the material to absorb vs reflect at whatever wavelength(s) you are using.

THanks Externet,

SO many ways to start a fire! Really trying to use the light from a distance.

cheers

Any electric light bulb can start fire with the glass removed and the incandescent element ignites a proper mixture of something at turn on.

An automotive cigarette lighter would last much longer on 12V, but its light is faint.

Hello,

I realise this sounds a little dubious as a request. I posted about making fire with the mid winter sun and it isn't enough to get the fire going (it is often cloudy for most of the day here) so I am trying electric light. I thought it would be quite good if I'm after the IR end of the spectrum for heat.

How can I estimate which type of bulb to use and the number of watts. they all feel quite weak at the moment and i'm not having much luck. (I thought this might be a safety feature to prevent house fires)

Many thanks for you help.

I am going to try tumble dryer fluff!

Ewmon,

Beautifully explained, and a useful IR tip.

Thanks very much.

Hello!

I am trying to start fire from the sun using a lens (from ice, water in a plastic bag and glasses) in Norway. I haven't had success.

The midwinter sun is much lower here as you can imagine. I am interested to know if the 'weaker' mid winter sun is less likely to begin a fire? and if there are physical ways around this. can I simply leave the tinder in the focus point for longer, or will it simply not get hot enough?

Many thanks.