00:01
Here we're looking at an electron and positron annihilation, to matter, antimatter annihilation, where each of the particles is coming into each other, a head -on collision, each has a kinetic energy of 430 -kil electron volts.
00:16
So the problem wants us to find the wavelengths of the photons produced in the annihilation.
00:24
Or if they were at rest, it would just be the conversion of the rest mass energy into gamma rays, but since they have connect guarantee, that you have to add in the connect energy.
00:38
So the first we have to find the total energy of each particle.
00:45
So that's the electron.
00:49
That is the k of the electron plus its rest mass energy.
01:00
That equals, so we're given 400 and and sorry, these are, it's supposed to be 420 kiloelectron volts.
01:19
So 420 kiloelectron volts is 0 .42 mega electron volts, plus its rest mass energy.
01:37
And similarly for the positron.
02:05
So these are both equal to 0 .931.
02:18
M .e .v.
02:21
So they're both going to release electron, i mean, they both can release photons of this energy...