Calculate the force ( magnitude and direction on the charge $q$ in the diagram where $\mathrm{q}=3.0 \mathrm{\mu C}$

Two plastic spheres of mass $100.0 \mathrm{mg}$ are suspended from a very fine insulating string of length $85.0 cm$. When equal charges are placed on the spheres, the spheres repel and are in equilibrium when $10 \mathrm{cm}$apart.

 Determine the charge on each sphere.

Two plastic spheres of mass $100.0 \mathrm{mg}$ are suspended from a very fine insulating string of length $85.0 cm$. When equal charges are placed on the spheres, the spheres repel and are in equilibrium when $10 \mathrm{cm}$apart.

 Determine the charge on each sphere. Estimate how many electron charges this corresponds to.

Consider two people, each of mass $60 \mathrm{kg}$, a distance of $10 \mathrm{m}$ apart. Assuming all the mass is made out of the water, estimate how many electrons there are in each person. Hence, estimate the electrostatic repulsive force between the two people due to the electrons.

List other simplifying assumptions you have made to make your estimate

Consider two people, each of mass $60 \mathrm{kg}$, a distance of $10 \mathrm{m}$ apart. Assuming all the mas is made out of the water, estimate how many electrons there are in each person. Hence, estimate the electrostatic repulsive force between the two people due to the electrons.

No such force is observed in practice. Suggest why this so.

The electric field is a vector and so two electric fields at the same point must be added according to the laws of vector addition. Consider two equal positive charges $q$, each of $2.00 \mathrm{\mu C}$, separated by $\mathrm{a}=10 \mathrm{cm}$ and a point $\mathrm{P}$ at a distance $\mathrm{d}=30 \mathrm{cm}$as shown in the diagram. The diagram shows the direction of the electric fields produced at $\mathrm{P}$ by each charge. Determine the magnitude and direction of net electric field at $\mathrm{P}$