Question

One milligram of matter is converted into energy. The energy released will be

• A. $9\times {10}^{6}J$
• B. $9\times {10}^{8}J$
• C. $9\times {10}^{10}J$
• D. $9\times {10}^{12}J$

Answer 1

The correct option is C $9\times {10}^{10}J$

Here, $m=1mg=1\times {10}^{-3}g$

$=1\times {10}^{-6}kg$
According to Einstein mass-energy equivalence

$E=m{c}^2$

where $c$ is the speed of light in vacuum

$\therefore E=(1\times {10}^{-6}kg)(3\times {10}^{8}m{s}^{-1}{)}^2$

$=9\times {10}^{10}J$.