How much energy in Joules be liberated if an electron of mass 9.11 x10-31 kg where converted to energy?

Answer 1

Well, E = M c2

E = (9.11 x 10-31) x (3 x 108)2 = 8.199 x 10-14 Joule

That's hardly a poof of a piffle, because we didn't start out with much mass.

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But wait ! Before you take your mass/energy converter and go home, let's

try a slightly different experiment and see what happens. Instead of just

a single electron, let's connect up a battery to a piece of wire and run

1 Ampere of current through the wire. Then we'll open up one end of

the wire, and let THOSE electrons drain into a bucket for 1 second.

NOW, laying in the bottom of the bucket, we'll have 1 ampere-second

of electrons = 6.25 x 1018 of those puppies. (They happen to be carrying

1 Coulomb of negative charge, but right now it's the MASS we're interested in.

We'll just drop an anti-cling drier sheet or something into the bucket, just

so we don't have to worry about the charge.)

The total mass of electrons in the bucket now is

(9.11 x 10-31) x (6.25 x 1018) = 5.69375 x 10-12 kg. Now we've got a whole 0.0000000057 gram, and we're starting to talk

some serious mass. Go ahead and pour THAT mass into the hopper of

your converter, and out of the spigot you'll get

E = M c2 = (5.69375 x 10-21) x (3 x 108)2 = 512,438 Joules THAT energy will run a 100-watt light bulb for 1hour25minutes.