The number of photons emitted per second by a 62 W source of monochromatic light of wavelength 4800 A0 is :
A monochromatic source of light operating at 200 W emits 4×1020 photons per second. The wavelength of this light will be __ nm.
A 100 Watt bulb emits monochromatic light of wavelength 400 nm. Calculate the number of photons emitted per second by the bulb.