THEORY OF GROUPING OF TWO DIFFERENT CELLS
– Two cells of different EMF and Internal Resistance in Series and Parallel.
1. When a number of cells are connected in series, the net emf is equal to the sum of their individual emfs.
E = E1 + E2 + . . . + En
2. If a cell (say E2) is connected oppositely, then E2 is to be replaced by –E2.
Hence E = E1 – E2 but r = r1 + r2.
ie. Internal resistance is always +ve irrespective of the way a cell is connected.
3. The emf of a cell is taken as +ve if current flows out of its +ve terminal (ie. when current inside the cell is from the –ve to the +ve)
4. The emf of a cell is independent of the external resistance connected in the circuit.
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