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The energy flux of sunlight reaching the...

The energy flux of sunlight reaching the surface of the earth is `1.388xx10^(3)W//m^(2)`. How many photons (nearly) per square metre are incident on the earth per second? Assume that the photons in the sunlight have an average wavelength of 550 nm.

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`E=1.388xx10^(3)Wm^(-2), lambda=550nm=550xx10^(-9)m`
`E=nh upsilon="nh"(c )/(lambda), n=(Elambda)/(hc)= (1.388xx10^(3)xx550xx10^(-9))/(6.63xx10^(-34)xx3xx10^(8))=3.8xx10^(21)" photon"//m^(2)//s`
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