State the principle of the Potentiometer.

A potentiometer is also called a voltmeter of infinite resistance, why?

A cell has an emf of 1.5 V. When short circuited, it gives a current of 3 A. The internal resistance of the cell is

A 2.0 V potentiometer is used to determine the internal resistance of a 1.5 V cell. The balance point of the cell in open circuit is 75 cm. When a resistor of 10 $\Omega$ is connected across the cell, the balance point shifts to 60 cm. The internal resistance of the cell is :

A potentiometer wire is 10 m long and has a resistance of $\rm 20 \;\Omega $. It is connected in series with a battery of emf 3 V and a resistance of $ \rm 10 \Omega $. The potential gradient along the wire in V/m is :

A potentiometer wire of length 10 m and resistance 30 $\rm \Omega$ is connected in series with a battery of emf 2.5 V with internal resistance 5 $\rm \Omega$ and an external resistance R. If the fall of potential along the potentiometer wire is 50 mV/m, the value of R is (in $\rm \Omega$)

Potentiometer measures potential more accurately because

A potentiometer wire of length 1 m and resistance 10 $\rm \Omega$ is connected in series with a cell of e.m.f. 2 V and internal resistance 1 $\rm \Omega$ and a resistance box including a resistance R. If the potential different between the ends of the wire is 1 m V, the value of R is

A potentiometer is more sensitive than a voltmeter because

In a potentiometer experiment, it is found that no current flows through the galvanometer when the terminals of the cell are connected across 125 cm of the potentiometer wire. On shunting the cell by 2 $\rm \Omega$ resistor, the balancing length is reduced to half. The internal resistance of the cell is

The resistivity of a potentiometer wire is 40 x 10$\rm ^{-8}$ ohm-m and its area of cross section is 8 x 10$\rm ^{-6}$ m$^2$. If 0.2 ampere current is flowing through the wire, the potential gradient will be 

A potentiometer consists of a wire of length 400 cm and of resistance 10 $\rm \Omega$. It is connected to a cell of e.m.f 2 volt having negligible internal resistance. Calculate the potential difference per unit length of the wire.