25. Electric Potential

An electron is in between charged capacitor plates. It is moved from a position near the positive plate to a position near the negative plate. What is true about the change in the potential and the change in the potential energy?

At one location in space the potential energy of a 10 nC charge is $12\mathrm{J}$. If the 10 nC charge was replaced with 20 nC charge at the same location, what would be the electrical potential energy of the 20 nC charge?

What is the electrical potential energy of the charges shown in the figure?

A small metal sphere, carrying a net charge of q_1 = -2.80 μC, is held in a stationary position by insulat­ing supports. A second small metal sphere, with a net charge of q_2 = -7.80 μC and mass 1.50 g, is projected toward q_1. When the two spheres are 0.800 m apart, q_2, is moving toward q_1 with speed 22.0 m/s (Fig. E23.5). Assume that the two spheres can be treated as point charges. You can ignore the force of gravity. (a) What is the speed of q_2 when the spheres are 0.400 m apart?

(a) How much work would it take to push two protons very slowly from a separation of 2.00x10^-10 m (a typical atomic distance) to 3.00x10^-15 m (a typical nuclear distance)? (b) If the protons are both released from rest at the closer distance in part (a), how fast are they moving when they reach their original separation?

A −3.0 nC charge is on the x-axis at x=−9 cm and a +4.0 nC charge is on the x-axis at x=16 cm. At what point or points on the y-axis is the electric potential zero?

The electric potential is 40 V at point A near a uniformly charged sphere. At point B, 2.0 μm farther away from the sphere, the potential has decreased by 0.16 mV. How far is point A from the center of the sphere?