Answer to Question #101651 in Electric Circuits for Janay Calice

Question

Three point objects have electrical charges and locations, as shown in the figure below to the left.
(a) Calculate the electrical potential energy U for this three-charge system.
(b) Calculate the electric potential V due to this three-charge system at a point 10.0 cm
directly above the 3.00 μC charge.

Answer 1

As the question image is missing,

So I am taking an assumption that there is 3 equal positive charges are situated at the vertices of the triangle. The magnitude of the charges are $q\mu C$ .and let the length of the side of the triangle is a cm.

a) So electric potential energy of the system = $\dfrac{q^2}{4\pi \epsilon_o a}+[\dfrac{q}{4\pi \epsilon_o a}-\dfrac{q}{4\pi \epsilon_o a}]$

Hence net electric potential energy due to the system$=\dfrac{q^2}{4\pi \epsilon_o a}$

b)Now point is just above the one vertices which have the charge = $3\mu C$ at 10cm above.

$=\dfrac{3q}{4\pi \epsilon_o \sqrt{a+10^2}}+\dfrac{3q}{4\pi \epsilon_o \sqrt{a+10^2}}+\dfrac{3q}{4\pi \epsilon_o 10}-\dfrac{3q}{4\pi \epsilon_o a}$

$=\dfrac{6q}{4\pi \epsilon_o \sqrt{a+10^2}} +\dfrac{3q}{4\pi \epsilon_o 10}-\dfrac{3q}{4\pi \epsilon_o a}$

As the diagram is missing, so i solved it as per the assumption.