[DeShark]

Originally Posted by DeShark

Your argument about blue light = more energy = more power produced by the calculator is not correct as I pointed out. The blue photons are not able to produce an electron hole as they have *too much* energy and hence cannot be absorbed. You can research all this yourself I'm sure and show me a webpage or quote a textbook. Big library here I'm sure I'll find a copy. Nice debate, it's causing me to remember my quantum phys from a-level. As well as teaching me various things about solar panels and LE bulbs.

I was in quite a rush when I first wrote that and wasn't quite thinking straight. In fact, I was almost talking gibberish. It's hard to explain all this without explaining the structure of the atom, absorption of a photon by an atom, electron excitation, covalent bonding and the effect of an incident (incoming) photon on such a covalent material. Thus I'll have to simplify the model somewhat.

In a typical solar panel (The things haven't changed much since their invention except in the purity of the silicon produced), there is a layer of a semi-conduction material (silicon with impurities embedded). The atoms in this layer share electrons with each other and the lorentz forces (electro-magnetic) between nuclei and electrons will keep the atoms and electrons held together. The electrons can be either "localised" (restricted to move around one or two atoms) or "delocalised" (free to move around the whole structure). (Roughly speaking) When the electrons are delocalised, the material is conductive but when the electrons are localised, the material is an electric insulator. When a metal (conductor) is subjected to incoming photons of high enough energy the electrons are given the energy of the photon which increases their speed enough for them to leave the metal completely (aka The photo-electric effect). In a semi-conductor (such as silicon) the electrons are on the border of conducting and non-conducting.

You could say your solar panel is like Goldilocks. If a photon comes in with too little energy, the electrons are unable to move into a free state. They remain "bound" to the atom and do not conduct. If a photon comes in with too much energy, the energy cannot be given to the electron. The energy is converted to heat. The silicon layer heats up and does not conduct. If however, the energy is "just right", the silicon layer becomes conductive, the electrons can flow freely and an electric current is induced. This amount of energy which is "just right" is known as the "band-gap energy". As I said before, for silicon it's about 1.1 eV (electron-volts). This is infrared light.

I really can't spell it out any more. The bottom line is that your calculator will NOT be activated by light from any source and it is NOT the brightness (or amount measured in lumins) of light falling on the solar panel that will determine at what point the calculator will become operative. It depends on the frequency of the light and how intense *that specific* frequency is.