Question

How much energy do 4,000,300,084 photons have in total if they have a wavelength of 600 nanometers? Have your answer in units of nanojoules.

Answer 1

we know that

energy of one photon = hc / λ

where, h = planck constant = 6.626 × 10^-34 m² kg / s

c = speed of light = 3 × 10⁸ m/s

  λ = wavelength = 600 nm

So,

energy of one photon of given wavelength

= (6.626 × 10^-34 m² kg / s × 3 × 10⁸ m/s) / 600 × 10^-9 m

energy of one photon of given wavelength = 3.3 × 10^-19 joule

now, we have given

nmber of photons are = 4,000,300,084 photons

therefore,

energy of 4,000,300,084 photons = 4,000,300,084 photons × energy of one photon

energy of 4,000,300,084 photons = 4,000,300,084 ×   3.3 × 10^-19

energy of 4,000,300,084 photons = 1.3201 × 10^-9 joule

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