Potentiometer

In an experiment with potentiometer, the balancing length is $250 \mathrm{cm}$ for a cell. When the cell is shunted by a resistance of $7.5 \mathrm{\Omega }$, the balancing point is shifted by $25 \mathrm{cm}$. If the cell is shunted by a resistance of $20 \mathrm{\Omega }$, the balancing length will be nearly
 

Balancing point of a potentiometer shifts from a length of $60 \mathrm{cm}$ to $40 \mathrm{cm}$ by shunting the cell with a $4 \Omega$ resistance. What is the internal resistance of the cell?

A potentiometer wire of length $L$ and resistance $10 \mathrm{\Omega }$ is connected in series with a battery of emf $2.5 \mathrm{V}$ and a resistance in its primary circuit. The null point corresponding to a cell of emf $1 \mathrm{V}$ is obtained at a distance $\frac{\mathrm{L}}{2}$. If the resistance in the primary circuit is doubled then the position of new null point will be

As shown in the figure, a potentiometer wire of resistance $20 \mathrm{\Omega }$ and length $300 \mathrm{cm}$ is connected with resistance box (R.B.) and a standard cell of emf $4 \mathrm{V}$. For a resistance '$R$' of resistance box introduced into the circuit, the null point for a cell of $20 \mathrm{mV}$ is found to be $60 \mathrm{cm}$. The value of '$R$' is _____ $\mathrm{\Omega }$.

A potentiometer wire of length $300 \mathrm{cm}$ is connected in series with a resistance $780 \mathrm{\Omega }$ and a standard cell of emf $4 \mathrm{V}$. A constant current flows through potentiometer wire. The length of the null point for cell of emf $20\mathrm{mV}$ is found to be $60 \mathrm{cm}$. The resistance of the potentiometer wire is _____ $\mathrm{\Omega }$.

In a potentiometer arrangement, a cell of emf $1.20 \mathrm{V}$ gives a balance point at $36 \mathrm{cm}$ length of wire. This cell is now replaced by another cell of emf $1.80 \mathrm{V}$. The difference in balancing length of potentiometer wire in above conditions will be _____ $\mathrm{cm}$.

A meter bridge setup is shown in the figure. It is used to determine an unknown resistance $R$ using a given resistor of $15 \mathrm{\Omega }$. The galvanometer $\left(G\right)$ shows null deflection when tapping key is at $43 \mathrm{cm}$ mark from end $A$. If the end correction for end $A$ is $2 \mathrm{cm}$, then the determined value of $R$ will be $\mathrm{\Omega }$.

A cell, shunted by a $8 \mathrm{\Omega }$ resistance, is balanced across a potentiometer wire of length $3 \mathrm{m}$. The balancing length is $2 \mathrm{m}$ when the cell is shunted by $4 \mathrm{\Omega }$ resistance. The value of internal resistance of the cell will be _____ $\mathrm{\Omega }.$

A potentiometer wire of length $10 \mathrm{m}$ and resistance $20 \mathrm{\Omega }$ is connected in series with a $25 \mathrm{V}$ battery and an external resistance $30 \mathrm{\Omega }$. A cell of emf $E$ in secondary circuit is balanced by $250 \mathrm{cm}$ long potentiometer wire. The value of $E$ (in volt) is $\frac{x}{10}$. The value of $x$ is _____ .

In a potentiometer arrangement, a cell gives a balancing point at $75 \mathrm{cm}$ length of wire. This cell is now replaced by another cell of unknown emf. If the ratio of the emf's of two cells respectively is $3:2$, the difference in the balancing length of the potentiometer wire in above two cases will be _____ $\mathrm{cm}$.

The length of potentiometer wire is $200 \mathrm{cm}$ and the emf of standard cell in primary circuit is $E$ volts. It is employed to a battery of emf $0.4 \mathrm{V}$, the balance point is obtained at $l=40 \mathrm{cm}$ from positive end, the $E$ of the battery is (cell in primary is ideal, and series resistance is zero)

In the following circuit diagram the resistance of potentiometer wire is $4\mathrm{\Omega }$ and its length is $100 \mathrm{cm}$. If the potential difference across $200\mathrm{\Omega }$ resistance box is $1 \mathrm{V}$, then the e.m.f. of cell in millivolt will be-

In a potentiometer if the magnitude of rheostat is increased then the balancing length. (The unknown emf remaining constant)

The emf of a cell is $2 \mathrm{V}$ and its internal resistance is $2\mathrm{ohm}$. A resistance of $8\mathrm{ohm}$ is joined to battery in parallel. This is connected in secondary circuit of potentiometer. If $1 \mathrm{V}$ standard cell balances for $100 \mathrm{cm}$ of potentiometer wire, the balance point of above cell is

In a potentiometer arrangement, a cell of emf $1.5 \mathrm{V}$ gives a Balance point a $150 \mathrm{cm}$ length of the wire. If the cell is replaced by another cell and the balance point shift to $210 \mathrm{cm}$, what is the $\mathrm{emf}$ of the second cell?

The figure shows a potentiometer arrangement. $D$ is the driving cell and $C$ is the cell whose emf is to be determined. $AB$ is the uniform potentiometer wire and $G$ is galvanometer. $J$ is sliding contact which can touch any point on $AB$. Which of the following are essential conditions for obtaining balance?

In the circuit shown in figure, $AB$ is a uniform wire of length $L=5 \mathrm{m}.$ It has a resistance of $2 \mathrm{\Omega } {\mathrm{m}}^{-1}$. When $AC=2.0 \mathrm{m}$, it was found that the galvanometer shows zero reading when switch $S$ is placed in either of the two positions $1$ or $2.$ Then,

Write down five disadvantage of the potentiometer.

What kind of precautions shpuld we take while using potentiometer?

A potentiometer is an accurate and versatile device to make electrical measurements of $\mathrm{emf}$ because the methods involves: