[jambutty]

Originally Posted by DeShark

P.S. The blue bulb will permit infrared emission to occur. Just touch the bulb to see how hot it gets. This heat will be radiated and used to power your calculator explaining why it works. Your lighter also emits infrared radiation as will your computer screeen.

Very true but how much heat does a torch with a blue filter over the lens produce that can have an affect on my calculator? Undoubtedly some infrared will filter through as well as will other spectral colours because the blue filter is unlikely to be a perfect blue.

The bottom line is that my calculator will be activated by light from any source and it is 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. Where the light comes from or what colour it is, is irrelevant. The blue end of the spectrum has more energy than the red end and therefore I conclude that more energy means a brighter light. With a 10% differential between the outer limits of the spectrum as shown by http://www.iee.cz/iwtpv04/6-Pociask.ppt slide number 32 it is hardly a major factor.

In any case the point being made applies to, presumably, a modern solar cell. My calculator is more than 20 years old.