A 100 W point source emits monochromatic light of wavelength 6000oA. Calculate the total number of photons emitted by the source per second.
A 100 Watt bulb emits monochromatic light of wavelength 400 nm. Calculate the number of photons emitted per second by the bulb.
A monochromatic source of light operating at 200 W emits 4×1020 photons per second. The wavelength of this light will be __ nm.