An electron and a positron are moving toward each other and each has speed 0.500c in the lab frame. (a) What is the kinetic energy of each particle? (b) The e+ and e- meet head-on and annihilate. What is the energy of each photon that is produced? (c) What is the wavelength of each photon? How does the wavelength compare to the photon wavelength when the initial kinetic energy of the e+ and e- is negligibly small.

An electron and a positron are moving toward each other and each has speed 0.500c in the lab frame. (a) What is the kinetic energy of each particle? (b) The e+ and e- meet head-on and annihilate. What is the energy of each photon that is produced? (c) What is the wavelength of each photon? How does the wavelength compare to the photon wavelength when the initial kinetic energy of the e+ and e- is negligibly small.