A) \[32\,\,\Omega \]
B) \[40\,\,\Omega \]
C) \[44\,\,\Omega \]
D) \[48\,\,\Omega \]
Correct Answer: A
Solution :
[a] Given, \[1=4\text{ }m,\] |
\[R=\] potentiometer wire resistance \[=8\,\Omega \] |
Potential gradient \[\frac{dV}{dr}=1mV/cm\] |
So, for \[400cm,\Delta V=400\times 1\times {{10}^{-3}}=0.4V\] |
Let a resistor \[{{R}_{s}}\] connected in series, so as |
\[\Delta V=\frac{V}{R+{{R}_{s}}}\times R\] |
\[\Rightarrow \] \[0.4=\frac{2}{8+R}\times 8\Rightarrow 8+R=\frac{16}{0.4}=40\] |
\[\Rightarrow \] \[R=32\,\Omega \] |
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