Practice question

**Electric field** defined as E = F/q₀, force per unit positive test charge, unit N/C or V/m, direction along force on positive test charge. For point charge, E = k q/r² radially outward for q>0. Field lines start on positive and end on negative, density indicates strength. Midpoint distance = 17.5 cm = 0.175 m. E₁ = 9 × 10⁹ × (5 × 10⁻⁶/(0.175)²) = 1.47 × 10⁶ N/C (towards -7 μC ). E₂ = 9 × 10⁹ × (7 × 10⁻⁶/(0.175)²) = 2.06 × 10⁶ N/C (towards -7 μC ). Net E = 1.47 × 10⁶ + 2.06 × 10⁶ = 3.53 × 10⁶