• # question_answer The momentum of a photon is $2\times {{10}^{-16}}$gm-cm/sec. Its energy is A) $0.61\times {{10}^{-26}}erg$ B) $2.0\times {{10}^{-26}}erg$ C) $6\times {{10}^{-6}}erg$ D) $6\times {{10}^{-8}}erg$

[c] $p=\frac{E}{c}\,\Rightarrow \,\,E=p\times c=2\times {{10}^{-16}}\times (3\times {{10}^{10}})$$=6\times {{10}^{-6}}erg.$