When cells are in series then the total emf is the sum of the emf of the cells
It makes no difference if there are components between the cells (including internal resistance)
The cells must be the same orientation in the circuit or the emf cancels out.
e(total) = e1 + e2 + ... + en
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Resistance in Circuits
Resistance in series adds together in a circuit: Rtotal = R1 + R2 + ... + Rn
Knowing the total resistance of a circuit allows the current flow through a circuit to be calculated. Remember that the current in a simple series circuit is the same everywhere:
I = e[total] / R[total]
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Celaculating PD across a resistor or component
Once you knoe (through measurement or calculation) the current flow in the circuit you can calculate the PD across the component:
V=IR
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Cells in Parallel
The total current in the circuit is split between the cells equally so far n cells the current through each must be 1/n
The output pd measured across the cell is the emf minus the "lost" pd from the internal resistance
V = e - (Ir) / n
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Resistance in Parallel
Resistance in parallel is calculated by:
(1/Rtotal) = (1/R1) + (1/R2) + ... + (1/Rn)
For identical resistors in parallel, the quicker calculation is:
Rtotal = R / n
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Diodes
Diodes are components that offer very high resistance in one direction so cuurent only passes one way
If it is not specified then assume a forward biased diode has a pf across it of 0.6V and infinite if reversed.
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