- Suppose the total charge Q is distributed uniformly over a ring-shaped with radius R. Find the electric potential at distance z above the center. Use: cm and
- The potential energy between two of neutral atoms or molecules is given by Lennard-Jones:

whereis the depth of the potential and is the distance at which the potential energy is zero.

- Based on a model the values of the parameters for water are: kJ/mol and Plot the potential energy versus distance for water.
- Calculate the electric force and plot it by using the finite difference method and compare it with the analytical function:

- A simple model of a long DNA is a long tiny cylinderwith radius of 1 nm and dielectric constant of and linear charge density of .

- Find the electric field at distance from DNA.
- Plot electric field versus distance for /nm and .
- Find electric potentialby using finite deference method and compare it with analytical solution: , ( ) where is the potential at and it is a constant and can be chosen equal zero.