AP EAMCET · PHYSICS · Current Electricity
Twelve cells, each having emf \(E\) volts 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 \(R\) ohms 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 \(2 \mathrm{~A}\) when they oppose each other. Then, the number of cells in 12-cell battery that are connected wrongly is :
- A 4
- B 3
- C 2
- D 1
Answer & Solution
Correct Answer
(D) 1
Step-by-step Solution
Detailed explanation
Let polarity of \(m\) cells in a 12 cells battery is reversed, then equivalent emf of the battery \(=(12-2 m) E\) Now the circuit can be drawn as : When 12-cell battery and 2-cell battery aid each other, then current through the circuit, \(i_1=\frac{(12-2 m) E+2 E}{R}\) or…
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