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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)Wm^(-2)`. The photons in the sunlight have an average wavelength of 550 nm.
How many photons per square meter are incident on the earth per second ?

A

`4xx10^(21)`

B

`4xx10^(34)`

C

`4xx10^(31)`

D

`4xx10^(28)`

Text Solution

Verified by Experts

The correct Answer is:
A
(a) : Here, `I=3.88xx10^(3)Wm^(-2)`
`lamda=550xx10^(-9)m,h=6.63xx10^(-34)J` s
Number of photons incident on earth's surface per second per square metre is
`n=(I)/(E)=(Ilamda)/(hc)" "( :. E=(hc)/(lamda))`
`=(1.388xx10^(3)xx550xx10^(-9))/(6.63xx10^(-34)xx3xx10^(8))=4xx10^(21)`
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Knowledge Check

  • The energy flux of sunlight reaching the surface of the earth is 1.388 xx 10^(3) W m^(-2) and the photons in the sunlight have an average wavelength of 550 nm. The number of photons per square metre that are incident on the earth per second is:

    A
    `4 xx 10 ^(21)`
    B
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    C
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    D
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  • A radio transmitter radiates 1 kW power at a wavelength 198.6 m . How many photons does it emit per second ?

    A
    `10^(10)`
    B
    `10^(20)`
    C
    `10^(30)`
    D
    `10^(40)`

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    B
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    C
    `2.5xx10^(19)`
    D
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