Cells in series (same direction)
EMF & Internal Resistance — AQA A-Level Physics
- Cells in series provide more energyThe capacity to do work. Measured in joules (J). per coulombThe SI unit of chargeA property of matter that causes it to experience a force in an electromagnetic field. Measured in coulombs (C).. One coulomb is the chargeA property of matter that causes it to experience a force in an electromagnetic field. Measured in coulombs (C). transferred by a current of 1 A in 1 second. to the circuit.
- If cells face the same direction: total EMFElectromotive force. The energy transferred per unit charge by a source in driving charge around a complete circuit. Measured in volts (V). = sum of individual EMFs.
- If cells face opposite directions: total EMFElectromotive force. The energy transferred per unit charge by a source in driving charge around a complete circuit. Measured in volts (V). = difference of EMFs.
- Total internal resistanceThe opposition to currentThe rate of flow of chargeA property of matter that causes it to experience a force in an electromagnetic field. Measured in coulombs (C).. Measured in amperes (A). flow. The ratio of potential difference to currentThe rate of flow of charge. Measured in amperes (A).. Measured in ohms (Ω). = sum of individual internal resistances.
- Example: Two cells (2.0 V and 1.5 V) in series, same direction: total EMFElectromotive force. The energy transferred per unit charge by a source in driving charge around a complete circuit. Measured in volts (V). $= 3.5$ V.
- Same cells in opposite directions: total EMF $= 2.0 - 1.5 = 0.5$ V.