A wire of length L and 3 identical cells of negligible internal resistance are connected in series. Due to the current, the temperature of the wire is raised by `DeltaT` in a time t. A number N of similar cells is now connected in series with a wire of the same material and cross-section but of length 2L. The temperature of the wire is raised by the same amount `DeltaT` in the same time t. the value of N isA. `4`B. `6`C. `8`D. `9`

A wire of length L and 3 identical cells of negligible internal resist

1.	A wire of length L and 3 identical cells of negligible internal resistance are connected in series. Due to the current, the temperature of the wire is raised by `DeltaT` in a time t. A number N of similar cells is now connected in series with a wire of the same material and cross-section but of length 2L. The temperature of the wire is raised by the same amount `DeltaT` in the same time t. the value of N isA. `4`B. `6`C. `8`D. `9`
Answer» Correct Answer - B `H=(V^(2))/Rt=mCDeltaTimplies((3E)^(2))/R t=RmCDeltaT` `(3E)^(2)t=rhoL/A(dAL)CDeltaT` `(3E)^(2)t=rhodL^(2)CDeltaT....(1)` `(nE)^(2)t=rhodL(2L)^(2)CDeltaL...(2)` From `(1)` and `(2), n=6`

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