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Help on Finding EMF and resistance watch

I cant seem to get a coherent set of equations.
any help would be much appreciated
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2. bump
3. you can calculate the PD across the 7 ohm external resistor in both cases...

cells in series
2E=2.331 + 2*r*0.311 [1]

cells in parallel
E=2.625 + 0.5*r*0.375 [2]

solve as simultaneous equations to get a value for r then sub back into either [1] or [2]
4. (Original post by 123Master321)

I cant seem to get a coherent set of equations.
any help would be much appreciated
Kirchhoff's laws might not be necessary in this question.
For series,
2E = I ( 2r + 7 )

For parallel,
E = I ( r/2 + 7)
Note: effective emf for parallel batteries will be just emf of one battery.

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