A $10 \,m$ long potentiometer wire is connected to a battery having a steady voltage. A Leclanche cell is balanced at $4 \,m$ length of the wire. If the length is kept the same, but its cross-section is doubled, the null point will be obtained at ........... $m$
A$8$
B$4$
C$2$
D
None of these
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B$4$
b (b)
If length is kept same, potential gradient remains same, so null point does not change.
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Two identical cells send the same current in $2\,\Omega $ resistance, whether connected in series or in parallel. The internal resistance of the cell should be ............... $\Omega$
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