25. Electric Potential

How far from a 5μC charge will the potential be 100 V?

A −1μC and a 5μC charge lie on a line, separated by 5cm. What is the electric potential halfway between the two charges?

A thin spherical shell with radius $R_1=3.00$ cm is concentric with a larger thin spherical shell with radius $R_2=5.00$ cm. Both shells are made of insulating material. The smaller shell has charge $q_1=+6.00$ nC distributed uniformly over its surface, and the larger shell has charge $q_2=-9.00$ nC distributed uniformly over its surface. Take the electric potential to be zero at an infinite distance from both shells. What is the electric potential due to the two shells at the following distance from their common center: (i) $r=0$; (ii) $r=4.00$ cm; (iii) $r=6.00$ cm?

Two stationary point charges $+3.00$ nC and $+2.00$ nC are separated by a distance of $50.0$ cm. An electron is released from rest at a point midway between the two charges and moves along the line connecting the two charges. What is the speed of the electron when it is $10.0$ cm from the $+3.00$-nC charge?

How much excess charge must be placed on a copper sphere $25.0$ cm in diameter so that the potential of its center, rela­tive to infinity, is $3.75$ kV? What is the potential of the sphere's surface relative to infinity?

Two large, parallel conducting plates carrying op­posite charges of equal magnitude are separated by $2.20$ cm. The surface charge density for each plate has magnitude $47.0$ nC/m^2. If the separation between the plates is doubled while the surface charge density is kept constant at the given value, what happens to the magnitude of the electric field and to the po­tential difference?