Equivalently, the smallness of the Planck constant reflects the fact that everyday objects and systems are made of a large number of particles. For example, green light with a wavelength of 555 nanometres (the approximate wavelength to which human eyes are most sensitive) has a frequency of 7014540000000000000♠540 THz (7014540000000000000♠540×1012 Hz). Each photon has an energy E = hf = 6981358000000000000♠3.58×10−19 J. That is a very small amount of energy in terms of everyday experience, but everyday experience is not concerned with individual photons any more than with individual atoms or molecules. An amount of light compatible with everyday experience is the energy of one mole of photons; its energy can be computed by multiplying the photon energy by the Avogadro constant, NA ≈ 7023602200000000000♠6.022×1023 mol−1. The result is that green light of wavelength 555 nm has an energy of 7005216000000000000♠216 kJ/mol, a typical energy of everyday life. COUNT 12
QSN1 What are common things like furniture and stationary objects actually made of? ANS1 particles QSN2 Which light wavelength is the human eye most sensitive to? ANS2 555 nanometres QSN3 What color of light is the human eye most sensitive to? ANS3 green QSN4 What does the smallness of the Planck constant show? ANS4 the fact that everyday objects and systems are made of a large number of particles QSN5 At about what wavelength of light are human eyes most sensitive? ANS5 555 nanometres QSN6 What frequency does green light with a wavelength of 555 nanmetres have? ANS6 7014540000000000000♠540 THz QSN7 How is the energy from one mole of photos computed? ANS7 by multiplying the photon energy by the Avogadro constant QSN8 How much energy does a green light of wavelength 555 nm contain? ANS8 7005216000000000000♠216 kJ/mol QSN9 What is the wavelength of light to which human eyes are most sensitive? ANS9 555 nanometres QSN10 What is the frequency of the light to which the human eye is most sensitive? ANS10 7014540000000000000♠540 THz QSN11 What is the energy of a photon? ANS11 6981358000000000000♠3.58×10−19 J QSN12 How much energy is contained in the light to which human eyes are most sensitive? ANS12 7005216000000000000♠216 kJ/mol