Question

When an electron-positron pair annihilates, the energy released is about :

• A. $0.8\times {10}^{-13}J$
• B. $1.6\times {10}^{-13}J$
• C. $3.2\times {10}^{-13}J$
• D. $4.8\times {10}^{-13}J$

Answer 1

The correct option is B $1.6\times {10}^{-13}J$

When electron-positron pair annihilates the energy released is due to conversion of mass into energy.
Total mass $=2\times 9\times {10}^{-31}kg$
Energy produced = $E=m{c}^2$
$=2\times 9\times {10}^{-31}\times (3\times {10}^8{)}^2$
$=162\times {10}^{-15}=1.62\times {10}^{-13}J$