Electrostatic?

Question

An electric charge accelerated from rest through a potential difference of 250V reaches a speed of 9.4 x 10^6m. What speed will this same charge reach if it is accelerated by a potential difference of 125V?

Answer 1

If you're keeping the distance bet'n the anode & cathode constant, the electric field is proportional to the voltage .

  Thus, half the previous voltage means that the field & consequently the acceleration is half of what was  before.

The final speed , too , is half : 4.7 * 10^6.

                However, the problem calls for relativistic corrections

:  9400 km/s is not a small speed.