# Two Spheres

**Electricity and Magnetism**Level 3

Two spheres that are \(35\text{ cm}\) apart have equal charge. How many excess electrons must be on each sphere if the magnitude of the force of repulsion between them is \(2.2\times10^{-21}\text{ N}\)?

Round your answer down to the nearest whole number.

**Details and Assumptions**:

- The charge of a single electron is \(e=1.6\times10^{-19}\text{ C}\).
- For this problem, assume the electrostatic constant is \(k_e=8.988\times10^9\text{ N m}^2\text{ C}^{-2}\).