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A uniform potentiometer wire AB of length 100 cm has a resistance of `5Omega` and it is connected in series with an external resistance R and a cell of emf 6 V and negligible internal resistance. If a source of potential drop 2 V is balanced against a length of 60 cm of the potentiometer wire, the value of resistance R isA. `1Omega`B. `2Omega`C. `4Omega`D. `6Omega` |
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Answer» Correct Answer - C Current through the potentiometer wire is `l=(6)/(R+5)` `thereforeV=(6xx3)/((R+5))` `2=(18)/(R+5)` `R+5=9` `R=4Omega`. |
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