Two charged metal spheres A and B are situated in a vacuum, as illustrated in the figure below.
The shortest distance between the surfaces of the spheres is 
. A movable point P lies along the line joining the centres of the two spheres, a distance 
from the surface of sphere A. The variation with distance of the electric field strength 
at point P is shown in the graph below.
Use the graph above to explain whether the two spheres have charges of the same, or opposite, sign.
A proton is at point P where 
. Use data from the graph above to determine the acceleration of the proton.
Use data from the graph to state the value of at which the rate of change of electric potential
is maximum. Give the reason for the value you have chosen.
.
.
