According to the quantum mechanics, electromagnetic radiation of frequency can be regarded as consisting of photons

According to the quantum mechanics, electromagnetic radiation of frequency ν can be regarded as consisting of photons of energy hν where h = 6.626 × 10^-34 J.s is the Planck’s constant.

(a) What is the frequency range of visible photons (400 nm to 700 nm)? What is the energy range of visible photons (both in J and in eV)?

(b) How many photons per second does a low power (1 mW) He-Ne laser (336 = λ nm) emit? A cell phone that emits 0.4Wof 850 MHz radiation? A microwave oven operating at 2.45 GHz generating a microwave power of 750 W? How many photons of the latter frequency have to be absorbed to heat up a glass of water (0.2 L, heat capacity of water 4.18 kJ.kg^-1.K^-1) by 10^oC? At a given power of an electromagnetic wave, do you expect a classical wave description to work better for radio frequencies or X-rays? Why? At what He-Ne laser power do you expect quantum effects to become important?