2009-06-01, 04:01 AM
Conservation of energy => the energy (heat in this case) doubles.
I fairly sure the glass takes in almost no energy, so that effect can be neglected.
Flaxative you're thinking of energy density. The lens packs the energy into a smaller spot, but it doesn't add energy. It doesn't matter if the target is heated by a ray 1cm² or 10cm², if you wait long enough for the heat to spread the sample will have the same temperature rise.
I fairly sure the glass takes in almost no energy, so that effect can be neglected.
Flaxative you're thinking of energy density. The lens packs the energy into a smaller spot, but it doesn't add energy. It doesn't matter if the target is heated by a ray 1cm² or 10cm², if you wait long enough for the heat to spread the sample will have the same temperature rise.