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A modern 200 W sodium street lamp emits ...

A modern 200 W sodium street lamp emits yellow light of wavelength 0.6 `mum`. Assuming it to be 25% efficient in converting electrical energy to light, the number of photons of yellow light it emits per second is

A

`1.5 xx10^20`

B

`6xx10^18`

C

`62xx10^20`

D

`3xx10^19`

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The correct Answer is:
A
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