NEET-XII-Physics
neet 2020 questions with solutions year:2020
- #15Light with an average flux of `` 20\,\Omega/cm^2 `` falls on a non-reflecting surface at normal incidence having surface area `` 20\,cm^2 `` . The energy received by the surface during time span of `` 1\,minute `` is :
(A) `` 10 \times 10^3J ``
(B) `` 12 \times 10^3J ``
(C) `` 24 \times 10^3J ``
(D) `` 48 \times 10^3J ``
digAnsr: CAns : Energy received = Intensity `` \times `` Area `` \times `` Time
`` I=\frac{E}{A} ``
`` E=IAt ``
`` =\frac{20}{10^{-4}}\times 20\times 10^{-4}\times 60 ``
`` =24 \times 10^{3}\,J ``