Ohm's Law in circuits with internal resistance Steps: - Current I = E / (R + r), where r is internal resistance. - For R = 10 Ω, I = 0.3 A: E = 0.3(10 + r). - For R = 5 Ω, I = 0.6 A: E = 0.6(5 + r). - Equate: 0.3(10 + r) = 0.6(5 + r) → 3 + 0.3r = 3 + 0.6r → 0.3r = 0 → r = 0 Ω; E = 0.3 × 10 = 3 V. Why C is correct: - The equations from Ohm's law directly solve to E = 3 V, matching both current readings with r = 0 Ω. Why the others are wrong: - A. 0.5 V gives maximum I = 0.5/5 = 0.1 A for R = 5 Ω, less than 0.6 A. - B. 2 V gives maximum I = 2/5 = 0.4 A for R = 5 Ω, less than 0.6 A. - D. 6 V with first reading implies r = 10 Ω, but then I = 6/15 = 0.4 A for …