Concentrating light

[allant]

My problem simply put is: Can a number of torches make a brighter spot than one torch ? Take a torch, now for the discussion assume the filament is a thin square of say 1mm^2, (mm^2 means square milimeters ) now all the electromagnetic radiation (including infrared etc not just the visible) is coming of a surface of 2mm^2 ( two sides) . Now if it's output is say 2 watts that means the total intensity is 1 watt per square millimeter. Now focus the torch on a spot of say 10mm square, and assume 1 percent of the energy reaches this spot, that equates to ; 2 * 1% / 100 mm ^2 = 0.001 Watts per mm^2 . Now focus 1001 torches on the same spot. If possible this should lead to 1.001 watts per square mm., which is greater than any of the individual torches.

Is this possible? I have a less than obvious argument that says it is not, but does not say why not. Can someone unconfuse me please?

 

[overdoze]

Hi allant, welcome.

If possible this should lead to 1.001 watts per square mm., which is greater than any of the individual torches.

Is this possible?

Sure it's possible. It's even doable. I think what you're confused about, is the difference between light emitted by one object, and light absorbed (or reflected). But it stands to reason that many torches will together emit correspondingly more light than one torch.

Even when the light is focused, if you look at all of the light in the system, you will find that the amount doesn't change. All you've done, is concentrate some of the total light on a region of space; that means the rest of space is less well illuminated for the given total light output.

 

[allant]

Ok now for the catch which was going to leave for later.

Suround the whole experiment in a container, turn the power off to the torches and heat the whole container to the temperature of the filaments. Now place a 1mm^2 filament in the spot light.

Now the origianl filamants shold be raditiating as before at the same rate. Are more watts falling on this new filamant than are being emitted by the torch filaments, and doesn't equalibrium rules mean that this "filament" will get hotter than the suroundings, violating the third law of Thermodynamics (entropy). I.e a place getting spontaneously hotter than the suroundings ?

Duh ?