Light is incident normally on a completely absorbing surface with an energy flux of $25\mathrm{ }\mathrm{W}\mathrm{ }\mathrm{c}{\mathrm{m}}^{-2}$ . If the surface has an area of $25\mathrm{ }\mathrm{c}{\mathrm{m}}^2$ , the momentum transferred to the surface in $\text{40}\text{min}$ time duration will be:

• A

  $6.3\times {10}^{-4}\mathrm{ }\mathrm{N}\mathrm{ }\mathrm{s}$
• Correct answer
  B

  $5.0\times {10}^{-3}\mathrm{ }\mathrm{N}\mathrm{ }\mathrm{s}$
• C

  $3.5\times {10}^{-6}\mathrm{ }\mathrm{N}\mathrm{ }\mathrm{s}$
• D

  $1.4\times {10}^{-6}\mathrm{ }\mathrm{N}\mathrm{ }\mathrm{s}$

Hence, the correct answer is option: 'B'.