A beam of white light is incident normally on a plane surface absorbing $70\%$ of the light and reflecting the rest. If the incident beam carries $10 \mathrm{W}$ of power, the force exerted by it on the surface is

• A

  $3.3\times {10}^{-8} \mathrm{N}$
• Correct answer
  B

  $4.33\times {10}^{-8} \mathrm{N}$
• C

  $2.3\times {10}^{-8} \mathrm{N}$
• D

  $3.53\times {10}^{-8} \mathrm{N}$

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