H2 Physics 14 - Electric Fields: Force and Potential Between Point Charges

What you will learn

• Two charges 30 cm apart: Q_A = +4 microC and Q_B = -2 microC; goal is force between them and potential at the midpoint.
• Coulomb's law: F = k |Q_A| |Q_B| / r^2 with k = 8.99 x 10^9; F is about 0.80 N, attractive because the charges have opposite signs.
• Potential is a scalar: V at the midpoint sums Q_A / 0.15 and Q_B / 0.15 algebraically.