Tweleve celles each having the same emf are connected in series and are kept in a closed box. Some of the cells are wrongly connected. This battery is connected in series with an ammeter and two cells identical with each other. The current is 3A when the cells and battery aid each other and 2A when the cells and battery oppose each other. How many cells are wrongly connected?

Tweleve celles each having the same emf are connected in series and ar

1.	Tweleve celles each having the same emf are connected in series and are kept in a closed box. Some of the cells are wrongly connected. This battery is connected in series with an ammeter and two cells identical with each other. The current is 3A when the cells and battery aid each other and 2A when the cells and battery oppose each other. How many cells are wrongly connected?
Answer» Solution :Let m cells are wrongly CONNECTED in the BATTERY and `epsilon_("net")=(12-2m)epsilon` When two cells aid the battery, the CURRENT `3=((12-2m)epsilon+2epsilon)/(R )"……(i)"` where R is the total resistance of the circuit. When two cells opposes the battery, then `2=((12-2m)epsilon-2epsilon)/(R )".....(ii)"` Solving above equations, we get `m=1` Hence one cell is wrongly connected in the battery.

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