What is the real mass of an electron?

Answer 1

Basically, the rest mass of an electron is the amount of energy in the mass a single electron has when it is not in motion and is the only mass in a system. Make sense? No? Let's back up a bit and then come forward.

When anything is moving, it has more energy than it had when it was standing still. And when an electron is moving, the electron has more mass because of a consequence to Albert Einstein's E=mc2. We don't see this relatavistic mass increase until we see a velocity approaching the speed of light, but it appears at any non-zero velocity. It's just that it's really, really tiny until the electron is moving at maybe 90% or more of the speed of light.

So if we look at an electron that is just hanging in space by itself, we can make a statement about its mass, and that mass will be the same, will be invarient, from one inertial frame to another. It will be the same from place to place. It's mass will be the same, and that's were we get the term invarient mass or rest mass. Let's go on one more step.

If we consider the equation we mentioned, the one that says E=mc2 as stated above, that's the so-called mass-energy equivalence. It states that energy (E) is equal to the mass (m) times the square of the speed of light (c, and its square, c2). If we consider the rest mass, and then take that mass and see how much energy that it can be converted into, we'll have the rest mass energy. And now we're back where we started and have brought you up to speed with the background physics. (We left out those pesky manifold things and stuck to the basics.) Need more information? A link is provided below.

Answer 2

• 9.109 382 15(45)×10−31

kg

• 5.485 799 0943(23)×10−4

u

• 8.187 104 38(41)×10−14

J/c2

• 0.510 998 910(13)

MeV/c

Answer 3

The mass of the positron is the same as the mass of the electron, about 0.511 MeV/c2 or about 9.11 x 10-31 kg.

Answer 4

An electron's rest energy is 0.511 MeV.

Answer 5

9.10938188 × 10-31 kilograms

Answer 6

zero