Monochromatic light of frequency $6.0 \times 10^{14}\,\, Hz$ is produced by a laser. The power emitted is $2 \times 10^{-3}\,\, W.$ The number of photons emitted, on the average, by the source per second is

  • [AIPMT 2007]
  • A

    $5 \times  10^{16}$

  • B

    $5 \times  10^{17}$

  • C

    $5 \times  10^{14}$

  • D

    $5  \times 10^{15}$$\;$

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