Question

If a proton and anti-proton come close to each other and annihilate, how much energy will be released?

• A. $1.5\times {10}^{-10}J$
• B. $3\times {10}^{-10}J$
• C. $4.5\times {10}^{-10}J$
• D. $2\times {10}^{-10}J$

Answer 1

Answer: (B)

$3\times {10}^{-10}J$

Mass of proton $=$ mass of anti-proton
$=1.67\times {10}^{-27}kg=1amu$
Energy equivalent to $1amu=931MeV$
So, energy equivalent to $2amu=2\times 931MeV$
$=1862\times {10}^6\times 1.6\times {10}^{-19}$
$=2.97\times {10}^{-10}J$
$=3\times {10}^{-10}J$