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A 200W sodium street lamp emits yellow l...

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

A

`6xx10^8`

B

`62xx10^20`

C

`3xx10^19`

D

`1.5xx10^20`

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