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The energy flux of sunlight reaching the...

The energy flux of sunlight reaching the surface of the earth is `1.388 xx10^(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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`4xx10^(21)" photons/m"^(2)s`
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