Estimating the following two numbers should be interesting. The first number will tell you why radio engineering do not need to worry much about photons. The second number tells you why our eye can never count photons, even in barely detetable light.
The number of photons emitted per second by a MW transmitter of 10 kW power emitting radio waves of wavelength 500 m.

Estimating the following numbers should be interesting. The number tells you why our eye can never count photons, even in barely detetable light. The number of photons entering the pupil of our eye per second corresponding to the minimum intensity of white light that we humans can perceive (~10^-10 Wm^-2) . Take the area of the pupil to be about 0.4 cm^2 , and the average frequency of white light to be about 6 xx 10^14 Hz .

In a photoelectric effect set up, a point source of light of power 3.2 xx10^(-3) W emits monoenergetic photons of energy 5eV.The source is located at a distance of a stationary metallic sphere of work function 3eV and radius 8xx10^(-3)m .The efficiency of photoelectron emission is one for every 10^(6) incident photons.Assume that the sphere is isolated and initially neutral and the photoelectrons are initially swept away after emission. Calculate the number of photoelectrons emitted per second.