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PRACTICE / EMF and internal resistance

Open terminals can hide an internal current

Two source branches connect in parallel with matching positive-terminal orientation. One has emf 14 V and series resistance 2 Ω; the other has emf 8 V and series resistance 4 Ω. No external load is attached.

What is the common terminal voltage?

Organize the givens & assumptions
  • First branch: 14 V, 2 Ω
  • Second branch: 8 V, 4 Ω
  • External load open

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. Both ideal emf elements may absorb or deliver energy.

  1. A14 V14\ \mathrm V
  2. B8 V8\ \mathrm V
  3. C11 V11\ \mathrm V
  4. D12 V12\ \mathrm V

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