Two charges lie on the x-axis, one at the origin and the other at 14.3m What is the potential (relative to infinity) due to these charges at a point at 7.1m measured from the origin on the x-axis?

 V = 2.52 10³ V

Explanation:

The electric potential for a point charge is

       V = k ∑

In this case the formula is

       V = k ()

distances are the absolute value

       r₁ =√ (7.1 -0)² = 7.1 m

       r₁ =√ (7.1 - 14.3)² = 7.2 m

we substitute

       V = 9 10⁹ (q₁ / 7.1 + q₂ / 7.2)

we have two possibilities

* different charges

         V = 9 10⁹ (q₁ / 7.1 + q₂ / 7.2)

* equal charges and same sign

          q₁ = q₂ = q

         V = 9 10⁹ q (1 / 7.1 + 1 / 7.2) = p 9 10⁹   0.2797

         V = 2.52 10⁹ q

if we assume a value of the charge, for example q = 1 10⁻⁶ c

           V = 2.52 10⁹ 1 10⁻⁶

            V = 2.52 10³ V

unlike poles attract

you get 2.3=1.21*\frac{a}2 or 4.6=1.21a or a=3.802 (b)

explanation: