Problem 72-2    Source:  Example 23-3 - TIPLER, Paul - MOSCA, Gene -    Book: Física - Vol. 2 - 5ª Edição - Ed. LTC - 2006.

Two point charges of +5 nC are on the axis x, one located at the origin and the other x = 8 cm , as shown in Figure 72-02.2. Determine:

a) the potential at point P₁ on the axis x in x = 4 cm.

b) the potential at point P₂ on the axis y in y = 6 cm.

Solution of the Problem 72-2   

Item a   

We must remember that the charge of the proton is equal to the charge of the electron, that is, q = 1.6 x 10^-19 C. So, we can determine the intensity of the electric field at the place where the electron is located, knowing that r = 0.053 nm = 5.3 x 10^-11 m and using the eq. 71-05. This way we have

Performing the calculation we find the module of the intensity of the electric field, or

Item b   

As we know the electric field and the charge of the electron, to find the electrical force to which the electron is subjected we can use the eq. 71-02.