Question

The energy of an electron mass is approximately equal to ?
(a)15.1ev (b)0.51Mev (c)1.51Kev (d)0.5Gev

Answer 1

we know that rest energy is given by

E=mc2

for an electron

m = 9.1*10-31 kg

and of course

c = 3x108 m/s

so, we get

E=9.1*10-31 X (3*108)2

E=9.1 X 9 X 10-15

E=81.9 X 10-15 J

Hope its correct

Answer 2

electron mass is about 9×10^-28and it requires 1.6 ×10^-19coloumb to get a ray of electron