Question

In a process called "positron-electron annihilation," a positron collides with an electron, and both particles are destroyed. During this process, the total mass of both particles is completely converted to energy in the form of gamma radiation. Determine the total energy given off when one positron collides with one electron resulting in annihilation. (Note: mass of positron = mass of electron = 0.000549 amu)

Answer 1

If we convert:

2 particle sof mass = energy

then, we must apply the energy / mass equvialence equation,

this is givne by Einstein's Famous equation

E = m*C^2

m = mass and C = speed of light

1 positron mass = 0.000549 amu

change to mass

1 amu = 6.022*10^23

0.000549 amu = x

x = (0.000549)/(6.022*10^23) = 9.116572*10^-28 g

then, change to kg = 9.116572*10^-28 g * 10^-3 kg / g = 9.116572*10^-31 kg

now,

we have two particles, so 2x(mass)

Total mass = (positron + electron) = 2*(9.116572*10^-31) = 1.82331*10^-30 kg

E = (1.82331*10^-30 kg )(3*10^8 m/s2 )^2

E = 1.6409*10^-13 J