A potentiometer circuit has been set up for finding the internal resistance of a given cell. The main battery, used across the potentiometer wire, has an emf of $2.0 \mathrm{~V}$ and a negligible internal resistance. The potentiometer wire itself is $4 \mathrm{~m}$ long, when the resistance R, connected across the given cell, has values of(i) Infinity(ii) $9.5 \Omega$The balancing lengths', on the potentiometer wire are found to be $3 \mathrm{~m}$ and $2.85 \mathrm{~m}$, respectively. The value of internal resistance of the cell is.Option A $\quad 0.25 \Omega$Option B $\quad 0.95 \Omega$Option C $\quad 0.5 \Omega$Option D $\quad 0.75 \Omega$

A potentiometer circuit has been set up for finding the internal resistance of a given cell. The main battery, used across the potentiometer wire, has an emf of $2.0 \mathrm{~V}$ and a negligible internal resistance. The potentiometer wire itself is $4 \mathrm{~m}$ long, when the resistance R, connected across the given cell, has values of(i) Infinity(ii) $9.5 \Omega$The balancing lengths’, on the potentiometer wire are found to be $3 \mathrm{~m}$ and $2.85 \mathrm{~m}$, respectively. The value of internal resistance of the cell is.Option A $\quad 0.25 \Omega$Option B $\quad 0.95 \Omega$Option C $\quad 0.5 \Omega$Option D $\quad 0.75 \Omega$

A potentiometer circuit has been set up for finding the internal resistance of a given cell. The main battery, used across the potentiometer wire, has an emf of $2.0 \mathrm{~V}$ and a negligible internal resistance. The potentiometer wire itself is $4 \mathrm{~m}$ long, when the resistance R, connected across the given cell, has values of
(i) Infinity
(ii) $9.5 \Omega$
The balancing lengths’, on the potentiometer wire are found to be $3 \mathrm{~m}$ and $2.85 \mathrm{~m}$, respectively. The value of internal resistance of the cell is.
Option A $\quad 0.25 \Omega$
Option B $\quad 0.95 \Omega$
Option C $\quad 0.5 \Omega$
Option D $\quad 0.75 \Omega$

Physics

A potentiometer circuit has been set up for finding the internal resistance of a given cell. The main battery, used across the potentiometer wire, has an emf of $2.0 \mathrm{~V}$ and a negligible internal resistance. The potentiometer wire itself is $4 \mathrm{~m}$ long, when the resistance R, connected across the given cell, has values of
(i) Infinity
(ii) $9.5 \Omega$
The balancing lengths’, on the potentiometer wire are found to be $3 \mathrm{~m}$ and $2.85 \mathrm{~m}$, respectively. The value of internal resistance of the cell is.
Option A $\quad 0.25 \Omega$
Option B $\quad 0.95 \Omega$
Option C $\quad 0.5 \Omega$
Option D $\quad 0.75 \Omega$

The correct option is C

Internal resistance,

$\mathrm{r}=\left(\frac{\mathrm{E}-\mathrm{V}}{\mathrm{V}}\right) \mathrm{R}=\left(\frac{\ell_{2}-\ell_{1}}{\ell_{2}}\right) \mathrm{R}$

$=\left(\frac{0.15}{2.85}\right)(9.5) \Omega=0.5 \Omega$

i

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More Material

Two cells of voltage 10V and 2V and internal resistances 10Ω and 5Ω respectively are connected in parallel with the positive end of the 10V battery connected to the negative pole of 2V battery. Find the effective voltage and effective resistance of the combination.

Suppose there is a circuit consisting of only resistances and batteries and we have to double all voltages and all resistances. Show that currents are unaltered.

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