Through what potential difference should an electron be accelerated to give it a speed of
(a) 0.6c, (b) 0.9c and (c) 0.99 ?
a) As we know the moving object appears to be heavier in the moving frame that’s because of Lorentz transformation known as apparent mass which is given by 
Where 
, V is velocity of moving object and C is speed of light in vacuum i.e. 
And 
is mass at rest
Kinetic energy gained by the electron will be due to change in mass of electron.
As the gain in kinetic energy is given by charge 
potential difference applied i.e. q
As 
b)Similarly for 0.9c
Kinetic energy gained by the electron will be due to change in mass of electron.
As the gain in kinetic energy is given by charge 
potential difference applied i.e. q
As 
c) Similarly for 0.99c
Kinetic energy gained by the electron will be due to change in mass of electron.
As the gain in kinetic energy is given by charge 
potential difference applied i.e. q
As 
