QUESTIONS

In figure, $AB$ is a potentiometer wire of length $100 \mathrm{cm}$. The cell of emf $3 \mathrm{V}$ has a negligible internal resistance. What is the reading in voltmeter $\mathrm{V}$, if $\mathrm{BC}$ is equal to $70 \mathrm{cm}$?

A $3 \mathrm{V}$ battery of internal resistance $1 \mathrm{\Omega }$ is joined to a sliding wire of length $100 \mathrm{cm}$ and resistance $5 \mathrm{\Omega }$. A voltmeter, which takes negligible current, is connected across $60 \mathrm{cm}$ length of the wire, What is the reading of the voltmeter?

A $3 \mathrm{V}$ battery of internal resistance $1 \mathrm{\Omega }$ is joined to a sliding wire of length $100 \mathrm{cm}$ and resistance $5 \mathrm{\Omega }$. A voltmeter, which takes negligible current, is connected across $60 \mathrm{cm}$ length of the wire, if the resistance of the voltmeter were $150 \mathrm{\Omega }$, then what would have its reading?

Potential difference across a potentiometer wire of length $4 \mathrm{m}$ is $2 \mathrm{V}$. Calculate the potential gradient of the potentiometer.

A $10 \mathrm{m}$ long potentiometer wire has a potential gradient of $0.0025 \mathrm{V}/\mathrm{cm}$ along its length. Calculate the length of the wire at which null-point is obtained for a $1.025 \mathrm{V}$ standard cell. Also, find the emf of another cell for which the null-point is obtained at $860 \mathrm{cm}$ length. What maximum PD can be measured by this potentiometer?

A potentiometer is being used to compare two resistances. The balancing length for a standard resistor $R=10.0 \Omega$ is $58.3 \mathrm{cm}$, while that for an unknown resistance $X$ is $68.5 \mathrm{cm}$. Determine the value of $X$. What would you do if you failed to find a null-point on the potentiometer wire $AB$?

A cell gives a balance with $85 \mathrm{cm}$ of a potentiometer wire. When the terminals of the cell are shorted through a resistance of $7.5 \mathrm{\Omega }$ a balance is obtained at $75 \mathrm{cm}$. Find the internal resistance of the cell.

A cell of emf $1.25 \mathrm{V}$ gives a balance point at $35.0 \mathrm{cm}$ length of a potentiometer wire. For another cell, the balance point shifts to $63.0 \mathrm{cm}$. What is the emf of the second cell?