In: Physics
A flat surface of dimensions 2 m by 2 m that is given a total charge of 400 μC uniformly distributed over the surface, and where a point charge +4 μC is fixed a distance 2 cm above the centre of the charged surface. A second point charge +16 nC, with mass 10 g, is placed at rest directly above the first point charge, at a distance 2 cm from the first point charge. The second point charge is released and accelerates directly away from the first point charge and charged surface. After some time, the second point charge is a distance 3.4 cm from the first point charge. What is the speed of the second point charge at this time?
The electric field due to a flat surface:
where is the surface charge density:
Charge on the surface:
Area=2x2
Therefore,
Electric field due to the other charge:
The electric potential:
where
and
Change in potential energy due to electric fields:
where
The gravitational potential energy change:
The total change in potential energy is the change in kinetic energy.
Therofore,