Answer to Question #305887 in Physics for stella

Question

1. Electron and proton are placed at two different locations (one charge at each location). The locations have the same electric potential. Do these charges have the same electric potential energy?

a. Yes, if the electric potentials at the two locations are the same, the electric potential energies are also the same, regardless of the sign and magnitude of the charges placed at these locations.

b. No, because the electric potential energy EPE at a given location depends on the charge placed at that location as well as the electric potential V.

c. Both A and B

d. None of the above

2. Two electric charges are separated by 1.5 m (q1=-3.70µC and q2=+5.10µC). Find the electric potential midway between them.

a. 9.11𝑥10⁴𝑉

c. 7.11𝑥10⁴𝑉

b. 8.11 𝑥10⁴𝑉

d. 6.11𝑥10⁴𝑉

Answer 1

1. b.

2. The electric potential midway between them is given as follows:

$$V = k\dfrac{q_1}{r} + k\dfrac{q_2}{r} = k\dfrac{q_1+q_2}{r}$$

where $r = 1.5m/2 = 0.75m$ is the distance from each charge to the midway point. Thus, obtain:

$$V = 9\times 10^9\cdot \dfrac{(-3.7 + 5.10)\times 10^{-6}}{0.75} \approx 1.7\times 10^4V$$

Answer. $1.7\times 10^4V$.