A $2\,mW$ laser operates at a wavelength of $500\,nm.$ The number of photons that will be emitted per second is [Given Planck’s constant $h = 6.6 \times 10^{-34}\,Js,$ speed of light $c = 3.0\times 10^8\,m/s$ ]

  • [JEE MAIN 2019]
  • A

    $1\,\times 10^{16}$

  • B

    $1.5\,\times 10^{16}$

  • C

    $2\,\times 10^{16}$

  • D

    $5\,\times 10^{15}$

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