An electron and a positron annihilate each other emitting tw

An electron and a positron annihilate each other, emitting two identical photons in the process What is the wavelength of these photons? The mass of an electron or positron is 9.11 10-31 kg and h6.63 x 10-34 Js. A) 2.43 x 10-12 m B) 3.07 x 10-12 m C) 1.73 x 10-12 m D) 3.46 x 10-12 m E 1.21 10-12 m

Solution

E = 2*m*c^2 :the rest mass on an electron is 8.18x10^-14 J

The total energy is:

E = 1.64x10^-13 J

Now one photon has the energy of 8.18x10^-14 J and using the formula

E = hf where h = planck\'s constant and f is the photon frequency,
f = E/h = 1.24x10^20 Hz
Wavelength: c/f = 2.43x10^-12 m