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PRACTICE / EMF and internal resistance

Predict a load through an equivalent source

Two parallel source branches have matching polarity: an 18 V source with 3 Ω in series and a 6 V source with 6 Ω in series. A 5 Ω load is attached across their common output rails.

What power is dissipated in the load?

Organize the givens & assumptions
  • Source branches: (18 V, 3 Ω) and (6 V, 6 Ω)
  • Load: 5 Ω

Constant ideal emf and positive Ohmic internal resistance over the stated interval; settled DC currents and negligible lead resistance. This is an assigned source model, not battery test data.

  1. A20 W20\ \mathrm W
  2. B39.2 W39.2\ \mathrm W
  3. C64.8 W64.8\ \mathrm W
  4. D7.2 W7.2\ \mathrm W

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