1. The total charge of the radium nucleus (which has 88 electrons) is 1.41x10^-17 Coloumbs. What is the magnitude of the force on an electron at a distance of 4.98 angstrom from the radium nucleus?

2. (Using the info from question 1) What would the magnitude of the force be if the distance of the electron from the nucleus were tripled?

3. What is the magnitude of the electric force between a proton and an electron when they are at a distance of 7.21 angstrom from each other?

4. What is the magnitude of the electric force between two protons inside a nucleus when they are at a distance of 7.21 fermi from each other?

5. What is the magnitude of the electric force between an 'up' and a 'down' quark inside a proton when they are at a distance of 0.844 fermi from each other? (The up quark has an electric charge of (+2/3)e, the down quark has an electric charge of (-1/3)e, where e is the elementary charge.)

6. In the most common isotope of Hydrogen the nucleus is made out of a single proton. When this Hydrogen atom is neutral, a single electron orbits around the nucleus. What is the ratio of the electric force and the gravitational force acting between the proton and the electron, when they are 3.81 angstrom away from each other? (Possibly useful constants: Coulomb constant: k = 8.987610⁹ N*m²/C², Universal Gravitational constant: G = 6.672610^-11 N*m²/kg², elementary charge: e = 1.602210^-19 C, electron mass: m_e = 9.109410^-31 kg, proton mass: m_p = 1.672610^-27 kg. You might also find the specific charges i.e. charge per mass ratios of the electron and the proton useful: electron: e/m_e = 1.758810¹¹ C/kg; proton: e/m_p = 9.578810⁷ C/kg.)