2 In a thundercloud, there may be electric charges of $q_t = +40.0\U{C}$
3 near the top of the cloud and $q_b = -40.0\U{C}$ near the bottom of
4 the cloud. These charges are separated by $r = 2.00\U{km}$. What is
5 the electric force on the top charge?
6 \end{problem*} % problem 5.34
9 We'll be using Coulomb's law for the electro-magnetic force (text p. 144):
11 F_e = k_e \frac{q_1 q_2}{r^2}
13 with $k_e = 8.99\E{9}\U{Nm$^2$/C$^2$}$.
17 F_e = 8.99\E{9}\U{Nm$^2$/C$^2$}
18 \frac{-40.0\U{C} \cdot 40.0\U{C}}{(2000\U{m})^2}
19 = -8.99\E{9}\U{Nm$^2$/C$^2$}
20 \left( \frac{40\U{C}}{2000\U{m}} \right)^2
21 = \ans{-3.596\E{6}\U{N}}
23 where the $-$ sign indicates an attractive force.