Lasers have become very small as well as very large. The active volume of a laser constructed of the semiconductor has a volume of only (smaller than a grain of sand) and yet it can deliver 5.0 mW of power at wavelength. We have to calculate the production rate of photons.

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As the wavelength of the laser light is , the energy of the photons emitted will be

As the power of the laser is 5.0 mW, the number of photons emitted per second by this laser will be