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  • Twelve cells, each having emf E volt are connected in series and are kept in a closed box. Some of these cells are wrongly connected with positive and negative terminals reversed. This 12

Twelve cells, each having emf E volt are connected in series and are kept in a closed box. Some of these cells are wrongly connected with positive and negative terminals reversed. This 12 cell battery is connected in series with an ammeter, an external
resistance R ohm and a two-cell battery (two cells of the same type used earlier, connected perfectly in series). The current in the circuit when the 12-cell battery and 2-cell battery aid each other is 3A and is 2A when they oppose each other. Then the number of cell is 12-cell battery that are connected wrongly is:

Option: 1

4


Option: 2

3


Option: 3

2


Option: 4

1


Answers (1)

best_answer

When ' n ' cells are reversely connected

\begin{aligned} & i_1=\frac{(12-2 n) E+2 E}{R}=3 \\ & i_2=\frac{(12-2 n) E-2 E}{R}=2 \end{aligned}
From eqns. (1) and (2);

\frac{14 E-2 n E}{10 E-2 n E}=\frac{3}{2} or n=1

Posted by

Irshad Anwar

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