KCET 2015 Physics Solved Paper

When all the cells are connected correctly, then
Equivalent emf = 4E and effective resistance = 4rIf one of the cell is connected wrongly then, effective internal resistance will remain unchanged while, equivalent emf is
E′=E(n−2m)
where n is total number of cells; m is number of wrongly connected cells.
Therefore,⇒ equivalent emf = 2E and effective internal resistance = 4r