A positron and an electron collide and annihilated to emit two gamma photons of same energy. Calculate the wavelengths in pm corresponding to this gamma emission. round off to near value.

+1e0+−1e0→2λ (photon of same energy)The mass of two electrons is converted into energy.The energy produced during emission of two photons=2×me×c2=2×9.108×10−31×3.0×1082=163.9×10−15JEnergy produced per photon =16.39×10−14J2=8.195×10−14JUsing Einstein equationE=hcλ, were c= velocity of light, λ= wavelength of  particle∴ 8.195×10−14=6.625×10−34×3.0×108λ∴ λ=6.625×10−34×3.0×1088.195×10−14=2.425×10−12mλ=2.425pm