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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 xx 10^(20)`

B

`6 xx 10^(18)`

C

`62 xx 10^(20)`

D

`3 xx 10^(19)`

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