Advertisements
Advertisements
प्रश्न
State the principle of a potentiometer. Define potential gradient. Obtain an expression for potential gradient in terms of resistivity of the potentiometer wire.
Advertisements
उत्तर
Principle
When a constant current is passed through a wire of uniform area of cross-section, the potential drop across any portion of the wire is directly proportional to the length of that portion.
Let V be the potential difference across certain portion of the wire, whose resistance is R. If I is the current through the wire, then \[V = IR\] We know that \[R = \rho\frac{l}{A}\], where l, A and ρ are length, area of cross-section and resistivity of the material of the wire, respectively.
\[\therefore V = I\rho\frac{l}{A}\]
\[ \Rightarrow \frac{V}{l} = \frac{I\rho}{A}\]
संबंधित प्रश्न
In a potentiometer experiment, balancing length is found to be 120 cm for a cell E1 of emf 2V. What will be the balancing length for another cell E2 of emf 1.5V? (No other changes are made in the experiment.)
Describe briefly, with the help of a circuit diagram, how a potentiometer is used to determine the internal resistance of a cell.
A voltmeter has a resistance of 100 Ω. What will be its reading when it is connected across a cell of emf 6 V and internal resistance 20 Ω?
To determine the internal resistance of a cell by using potentiometer, the null point is at 1 m when cell is shunted by 3 Ω resistance and at a length 1.5 m when cell is shunted by 6 Ω resistance. The internal resistance of the cell is ______.
A potentiometer wire is 10 m long and has resistance of 2`Omega`/m. It is connected in series with a battery of e.m.f 3 V and a resistance of 10 `Omega`. The potential gradient along the wire in V/m is ______.
When two cells of e.m.f 1.5 V and 1.1 V connected in series are balanced on a potentiometer, the balancing length is 260 cm. The balancing length, when they are connected in opposition is (in cm) ____________.
Two identical thin metal plates has charge q1 and q2 respectively such that q1 > q2. The plates were brought close to each other to form a parallel plate capacitor of capacitance C. The potential difference between them is ______.
If you are provided a set of resistances 2Ω, 4Ω, 6Ω and 8Ω. Connect these resistances so as to obtain an equivalent resistance of `46/3`Ω.
What is the effect of decreasing the current through the potentiometer on the null point?
Draw neat labelled diagram of potentiometer as voltage divider.
