Introduction to Coulomb's Law + examples. Force between proton and electron in Hydrogen atom.

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In this introduction to Coulomb's law, we start by reviewing the direction of electric force for like and unlike charges. Next, we introduce Coulomb's law which describes the magnitude of the electric force as a function of separation distance and charge, in addition to describing the repulsion or attraction using a +/- sign, so Coulomb's Law governs the electrostatic force between two charges.

We finish by working two examples using Coulomb's law to calculate electrostatic force between point charges. In the first example, we find the electrical force between two +1 micro-Coulomb charges separated by a meter. In the second example, we calculate the force of attraction between the proton and electron in a hydrogen atom, assuming a classical atom and a diameter of 1 Angstrom. The electric force in the hydrogen atom provides centripetal force to curve the path of the electron into an orbit (in this simple classical model).

[faredoondastur]

When there are two charges, one positive and the other negative, as I understand the direction of the electric force goes from the positive point charge to the negative one. In an atom however, it the negatively charge electron is pulled into the positively charged nucleus, which makes the direction of the electric force from the negative point charge to the positive one. Can you please explain to me how this difference works? Many thanks.