A cube of side b has a charge q at each of its vertices. Determine the potential and electric field due to this charge array at the centre of the cube.
Four point charges Q, q, Q and q are placed at the corners of a square of side 'a' as shown in the figure.
1) resultant electric force on a charge Q, and
2) potential energy of this system.
If one of the two electrons of a H2 molecule is removed, we get a hydrogen molecular ion `H_2^+`. In the ground state of an `H_2^+` , the two protons are separated by roughly 1.5 Å, and the electron is roughly 1 Å from each proton. Determine the potential energy of the system. Specify your choice of the zero of potential energy.