KCET2015PhysicsElectrostatics
Four identical cells of emf ( E ) and internal resistance ( r ) are to be connected in series. Suppose if one of the cell is connected wrongly, the equivalent emf and effective internal resistance of the combination is
Options
- A( 4 E ) and ( 4 r )
- B( 4 E ) and ( 2 r )
- C( 2 E ) and ( 4 r )
- D( 2 E ) and ( 2 r )
Correct answer
C. ( 2 E ) and ( 4 r )
Step-by-step solution
When all the cells are connected correctly, then Equivalent emf = 4E and effective resistance ( =4 r ) If one of the cell is connected wrongly then, effective internal resistance will remain unchanged while, equivalent emf is ( E^ =E(n-2 m) ) where ( n ) is total number of cells; ( m ) is number of wrongly connected cells. Therefore, ( E=E(4-2 1)=E(4-2)=2 E ) ( ) equivalent emf ( =2 E ) and effective internal resistance ( =4 r )