According to the first law: i 1 − − i 2 − − i 3 = 0 Applying the second law to the closed circuit s 1, and substituting for voltage using Ohm's law gives: − − R 2 i 2 + E 1 − − R 1 i 1 = 0 The second law, again combined with Ohm's law, applied to the closed circuit s 2 gives: − − R 3 i 3 − − E 2 − − E 1 + R 2 i 2 = 0