Two point charges are separated by 10.0 cm and have charges of +2.00 µC and -2.00 µC,respectively.What is the electric field at a point midway between the two charges? (k_e = 8.99 x 10⁹ N·m²/C²)

Question

Quizplus · Accepted Answer

Using the formula for electric field due to a point charge: 
E = (k|Q|)/r^2 
where k is Coulomb's constant, Q is the charge and r is the distance from the point charge.

At the midpoint, the distance from each charge is 5 cm. Therefore, the electric field due to each charge is:

E1 = (8.99 × 10^9 N·m^2/C^2) × (2.00 × 10^-6 C) / (0.05 m)^2 = 7.19 × 10^4 N/C 
E2 = (8.99 × 10^9 N·m^2/C^2) × (2.00 × 10^-6 C) / (0.05 m)^2 = 7.19 × 10^4 N/C

The electric fields are in opposite directions, so we must subtract to find the net electric field:

E = E1 - E2 = 0

Therefore, the electric field at the midpoint is zero. The correct choice is B.

Two Point Charges Are Separated by 10