A $160 \,W$ light source is radiating light of wavelength $6200 \,\mathring A$ uniformly in all directions. The photon flux at a distance of $1.8 \,m$ is of the order of .......... $m ^{-2} s ^{-1}$ (Planck's constant $\left.=6.63 \times 10^{-34} \,J - s \right)$

  • [KVPY 2014]
  • A

    $10^2$

  • B

    $10^{12}$

  • C

    $10^{19}$

  • D

    $10^{25}$

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