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InterviewSolution
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Estimating the following two numbers should be interesting. Thefirst number will tell you why radio engineers do not need to worrymuch about photons! The second number tells you why our eye cannever ‘count photons’, even in barely detectable light. (a) The number of photons emitted per second by a Medium wavetransmitter of 10 kW power, emitting radiowaves of wavelength500 m. (b) The number of photons entering the pupil of our eye per secondcorresponding to the minimum intensity of white light that we humans can perceive (∼10–10 W m–2). Take the area of the pupilto be about 0.4 cm2, and the average frequency of white light to be about 6 × 1014 Hz. |
| Answer» Estimating the following two numbers should be interesting. Thefirst number will tell you why radio engineers do not need to worrymuch about photons! The second number tells you why our eye cannever ‘count photons’, even in barely detectable light. (a) The number of photons emitted per second by a Medium wavetransmitter of 10 kW power, emitting radiowaves of wavelength500 m. (b) The number of photons entering the pupil of our eye per secondcorresponding to the minimum intensity of white light that we humans can perceive (∼10–10 W m–2). Take the area of the pupilto be about 0.4 cm2, and the average frequency of white light to be about 6 × 1014 Hz. | |