Question

Two balloons have equal and opposite charges. Balloon one has N = 10⁸ excess electrons. The balloons are separated by d = 1.3 m and each electron has a negative charge of e = 1.602 × 10^-19 C.

Answer 1

I assume, the task is to find the force of interation between the balloons.

Since the balloon one has $N = 10^8$ excess electrons and each electron has the charge $e = -1.602\times 10^{-19}C$, the total charge of the balloon is:

$$q_1 = -1.602\times 10^{-19}\cdot 10^8C = -1.602\times 10^{-11}C$$

Since the second balloon has equal and opposite charge, obtain:

$$q_2 = -q_1 = 1.602\times 10^{-11}C$$

The magnitude of the force between two balloons is given by the Coulomb's law:

$$F = k\dfrac{|q_1||q_2|}{d^2}$$

where $d = 1.3$ is the distance between the balloons, and $k = 9\times 10^{9}N\cdot m^2/C^2$ is the Coulomb's constant. Thus, obtain:

$$F = 9\times 10^{9}\dfrac{|-1.602\times 10^{-11}||1.602\times 10^{-11}|}{1.3^2} \approx 1.37\times 10^{-12}N$$

Answer. $1.37\times 10^{-12}N$.