Question

Person connects four cells in series but one cell has its terminal reversed. the internal resistance is 0.25 Ohm. If Each cell has an emf of 1.5 V the current flowing is? - a) 1 A b) 2.5 A c) 1.5 A d) zero

Answer 1

Here 4 cells each having emf `e=1.5V` and internal resistance `r=0.25Omega` are connected in series. So total resistance of the circcuit will be `4*r=4*0.25=1Omega`

As one of the cell is connected in reverse direction the effective emf becomes `E=3*e-e=2e=2*1.5=3V`

Hence current in the circuit

`I="net emf"/"total resistance"`

`=3/1=3A`