Question

Two point charges, -25?C and +60?C , are separated by a distance of 22.0cm .

What is the magnitude of the electric field at a point halfway between the two charges?

Answer 1

q₁ = -25 C = -25 * 10^-6 C

q₂ = +60 C = 60 * 10^-6 C

Separation between two charges is d = 22.0 cm = 22 * 10^-2 m

Since we need to calculate electric field at a point halfway between two charges, r = 11 * 10^-2 m

Magnitude of the electric field at a point due to two charges is given by

E = k q₁ / r² + k q₂ / r²                    where k = 8.99 * 10⁹ N.m²/ C² is the Coulomb's force constant.

Substituting the values we get,

E = 8.99 * 10⁹ * 25 * 10^-6 / (11 * 10^-2)² + 8.99 * 10⁹ * 60 * 10^-6 / (11 * 10^-2)²

E = 1.857 * 10⁷ + 4.458 * 10⁷

E = 6.315 * 10⁷ N/C