Two positively charged metal spheres A and B are situated in a vacuum, as shown in the figure below.
A point P lies on the line joining the centres of the two spheres and is a distance 
from the surface of sphere A. The variation with x of the electric potential 
due to the two charged spheres is shown in the graph below.
State how the magnitude of the electric field strength at any point P may be determined from the graph above.
Without any calculation, describe the force acting on a positively charged particle placed at point P for values of from 
to 
.
The positively charged particle in (a)(ii) has charge 
and mass 
given by the expression
Initially, the particle is at rest on the surface of sphere A where . It then moves freely along the line joining the centres of the spheres until it reaches the surface of sphere B.
Use the graph above to determine the potential difference between the spheres.
Use your answer in (ii) part 1 to calculate the speed of the particle as it reaches the surface of sphere B. Explain your working.
and then increases again but in opposite direction till 
.
.
