Two particles with charges +6e and -6e are initially very far apart (effectively an infinite distance apart). They are then fixed at positions that are 5.61 x 10^-12 m apart. What is EPEfinal - EPEinitial, which is the change in the electric potential energy?

Respuesta :

Answer:

[tex]\rm EPE_{final}-EPE_{initial}=-1.478\times 10^{-15}\ J.[/tex]

Explanation:

Given charges are:

[tex]\rm q_1 = +6e.\\q_2 = -6e.[/tex]

The electric potential energy of a charge due to the electric field of another charge is given by

[tex]\rm EPE=\dfrac{kq_1q_2}{r}.[/tex]

where,

  • k = Coulomb's constant, having value = [tex]\rm 9\times 10^9\ Nm^2/C^2.[/tex]
  • r = distance between the charges.

When the charges are infinite distance apart, [tex]\rm r = \infty[/tex],

[tex]\rm EPE_{initial} = \dfrac{kq_1q_2}{r}=0\ J.[/tex]

When the charges are [tex]\rm 5.61\times 10^{-12}\ m[/tex] apart, [tex]\rm r=5.61\times 10^{-12}\ m[/tex],

[tex]\rm EPE_{final}=\dfrac{kq_1q_2}{r}\\=\dfrac{(9\times 10^9)\times (+6e)\times (-6e)}{5.61\times 10^{-12}}\\=-5.775\ e^2\times 10^{22}.[/tex]

Here, e is the charge on one electron, such that, [tex]\rm e = -1.6\times 10^{-19}\ C[/tex].

Therefore,

[tex]\rm EPE_{final}=-5.775\times (-1.6\times 10^{-19})^2\times 10^{22} = -1.478\times 10^{-15}\ J.[/tex]

Thus,

[tex]\rm EPE_{final}-EPE_{initial}=-1.478\times 10^{-15}-0=-1.478\times 10^{-15}\ J.[/tex]