Problem 12.

  Suppose that of hydrogen is separated into its constituent protons and electrons, and that the protons are all grouped together at one point, and the electrons at another point, 3 meter distant. What is the magnitude of the force between the two groups of charge?

Solution

The first step is to find how many protons (and correspondingly electrons) there are in of hydrogen. To find this number we just need to divide the total mass by the mass of a single proton:

Then the charge of all protons grouped is (where is the proton charge), while the charge of all electrons grouped is . Then the magnitude of the Coulomb force is