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प्रश्न
State the uses of a potentiometer.
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उत्तर १
The applications of the potentiometer discussed above are used in a laboratory. Some practical applications of the potentiometer are given below.
- Voltage divider: The potentiometer can be used as a voltage divider to change the output voltage of a voltage supply.
- Audio control: Sliding potentiometers are commonly used in modern low-power audio systems as audio control devices. Both sliding (faders) and rotary potentiometers (knobs) are regularly used for frequency attenuation, loudness control and for controlling different characteristics of audio signals.
- Potentiometer as a sensor: lf the slider of the potentiometer is connected to the moving part of a machine, it can work as a motion sensor. A small displacement of the moving part causes a change in potential which is further amplified using an amplifier circuit. The potential difference is calibrated in terms of displacement of the moving part.
- To measure the emf (for this, the emf of the standard cell and potential gradient must be known).
- To compare the emfs of two cells.
- To determine a cell’s internal resistance.
उत्तर २
a. Potentiometer as a voltage Divider:
1. The potentiometer can be used as a voltage divider to continuously change the output voltage of a voltage supply. 
2. As shown in the above figure, potential V is set up between points A and B of a potentiometer wire.
3. One end of a device is connected to positive point A and the other end is connected to a slider that can move along wire AB.
4. The voltage V gets divided in the proportion of lengths l1 and l2, such that
V1 = `(dV(l))/(dL)` and
V2 = `(dV(L - l_1))/(dL)`
b. Potentiometer as an audio control:
1. Sliding potentiometers are commonly used in modern low-power audio systems as audio control devices.
2. Both sliding (faders) and rotary potentiometers (knobs) are regularly used for frequency attenuation, loudness control, and for controlling different characteristics of audio signals.
c. Potentiometer as a sensor:
1. If the slider of a potentiometer is connected to the moving part of a machine, it can work as a motion sensor.
2. A small displacement of the moving part causes changes in potential which is further amplified using an amplifier circuit.
3. The potential difference is calibrated in terms of the displacement of the moving part.
संबंधित प्रश्न
Figure shows a potentiometer with a cell of 2.0 V and internal resistance 0.40 Ω maintaining a potential drop across the resistor wire AB. A standard cell which maintains a constant emf of 1.02 V (for very moderate currents up to a few mA) gives a balance point at 67.3 cm length of the wire. To ensure very low currents drawn from the standard cell, very high resistance of 600 kΩ is put in series with it, which is shorted close to the balance point. The standard cell is then replaced by a cell of unknown emf ε and the balance point found similarly, turns out to be at 82.3 cm length of the wire.
(a) What is the value ε?
(b) What purpose does the high resistance of 600 kΩ have?
(c) Is the balance point affected by this high resistance?
(d) Is the balance point affected by the internal resistance of the driver cell?
(e) Would the method work in the above situation if the driver cell of the potentiometer had an emf of 1.0 V instead of 2.0 V?
(f) Would the circuit work well for determining an extremely small emf, say of the order of a few mV (such as the typical emf of a thermo-couple)? If not, how will you modify the circuit?
In the given circuit, with steady current, calculate the potential drop across the capacitor and the charge stored in it.
In the given circuit in the steady state, obtain the expressions for (a) the potential drop (b) the charge and (c) the energy stored in the capacitor, C.
Figure shows a long potentiometer wire AB having a constant potential gradient. The null points for the two primary cells of emfs ε1 and ε2 connected in the manner shown are obtained at a distance of l1 = 120 cm and l2 = 300 cm from the end A. Determine (i) ε1/ε2 and (ii) position of null point for the cell ε1 only.
Would you prefer a voltmeter or a potentiometer to measure the emf of a battery?
The net resistance of a voltmeter should be large to ensure that ______________ .
In a potentiometer experiment, the balancing length with a resistance of 2Ω is found to be 100 cm, while that of an unknown resistance is 500 cm. Calculate the value of the unknown resistance.
Draw a labelled circuit diagram of a potentiometer to measure the internal resistance ‘r’ of a cell. Write the working formula (derivation is not required).
Draw a labelled circuit diagram of a potentiometer to compare emfs of two cells. Write the working formula (Derivation not required).
Define a Potentiometer.
Distinguish between a potentiometer and a voltmeter.
Describe how a potentiometer is used to compare the EMFs of two cells by connecting the cells individually.
Describe with the help of a neat circuit diagram how you will determine the internal resistance of a cell by using a potentiometer. Derive the necessary formula.
A battery of emf 4 volt and internal resistance 1 Ω is connected in parallel with another battery of emf 1 V and internal resistance 1 Ω (with their like poles connected together). The combination is used to send current through an external resistance of 2 Ω. Calculate the current through the external resistance.
The resistance of a potentiometer wire is 8 Ω and its length is 8 m. A resistance box and a 2 V battery are connected in series with iL What should be the resistance in the box if it is desired to have a potential drop of 1 µV/mm?
The emf of a cell is balanced by a length of 120 cm of a potentiometer wire. When the cell is shunted by a resistance of 10 Ω, the balancing length is reduced by 20 cm. Find the internal resistance of the cell.
The instrument which can measure terminal potential difference as well as electromotive force (emf) is ______
State any one use of a potentiometer.
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?
What are the disadvantages of a potentiometer over a voltmeter?
Which of the following instruments is not a direct reading instrument?
Two cells having unknown emfs E1 and E2 (E1 > E2) are connected in potentiometer circuit, so as to assist each other. The null point obtained is at 490 cm from the higher potential end. When cell E2 is connected, so as to oppose cell E1, the null point is obtained at 90 cm from the same end. The ratio of the emfs of two cells `("E"_1/"E"_2)` is ______.
The potentiometer is more sensitive, when ______.
A potentiometer is an ideal device for measuring potential difference because ______.
A potentiometer wire has length L For given cell of emf E, the balancing length is `"L"/3` from 3 the positive end of the wire. If the length of the potentiometer wire is increased by 50%, then for the same cell, the balance point is obtained at length.
Which of the following is true for a potentiometer?
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 ______.
Sensitivity of a given potentiometer can be decreased by ______.
A potentiometer wire of length 100 cm has a resistance of 10 `Omega.` It is connected in series with a resistance and an accumulator of e.m.f 2 V and of negligible internal resistance. A source of e.m.f 10 mV is balanced against a 40 cm length of the potentiometer wire. The value of the external resistance 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 ______.
In the given figure, battery E is balanced on 55 cm length of potentiometer wire but when a resistance of 10 `Omega` is connected in parallel with the battery, then it balances on 50 cm length of the potentiometer wire. The internal resistance r of the battery is ____________.
A potentiometer is used to measure the potential difference between A and B, the null point is obtained at 0.9 m. Now the potential difference between A and C is measured, the null point is obtained at 0.3 m. The ratio `E_2/E_1` is (E1 > E2) ______
A wire has a length of 2m and a resistance of 10Ω. It is connected in series with a resistance of 990Ω and a cell of e.m.f. 2V. The potential gradient along the wire will be ______
In the experiment to determine the internal resistance of a cell (E1) using a potentiometer, the resistance drawn from the resistance box is 'R'. The potential difference across the balancing length of the wire is equal to the terminal potential difference (V) of the cell. The value of internal resistance (r) of the cell is ______
The sensitivity of the potentiometer can be increased by ______.
A potentiometer wire is 100 cm long and a constant potential difference is maintained across it. Two cells are connected in series first to support one another and then in opposite direction. The balance points are obtained at 50 cm and 10 cm from the positive end of the wire in the two cases. The ratio of emf's is ______.
In a potentiometer of 10 wires, the balance point is obtained on the 7th wire. To shift the balance point to 9th wire, we should ______.
AB is a wire of potentiometer with the increase in value of resistance R, the shift in the balance point J will be:
The value of current I in the network shown in fig.
What is the current I in the circuit as show in fig.
In a potentiometer circuit a cell of EMF 1.5 V gives balance point at 36 cm length of wire. If another cell of EMF 2.5 V replaces the first cell, then at what length of the wire, the balance point occurs?
In an experiment with a potentiometer, VB = 10V. R is adjusted to be 50Ω (Figure). A student wanting to measure voltage E1 of a battery (approx. 8V) finds no null point possible. He then diminishes R to 10Ω and is able to locate the null point on the last (4th) segment of the potentiometer. Find the resistance of the potentiometer wire and potential drop per unit length across the wire in the second case.
A Daniel cell is balanced on 125 cm lengths of a potentiometer wire. Now the cell is short circuited by a resistance 2 Ω and the balance is obtained at 100 cm. The internal resistance of the Daniel cell is ______.
In a potentiometer arrangement, a cell of emf 1.20 V gives a balance point at 36 cm length of wire. This cell is now replaced by another cell of emf 1.80 V. The difference in balancing length of potentiometer wire in above conditions will be ______ 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 value of resistance for an ideal voltmeter?
What should be the diameter of a soap bubble such that the excess pressure inside it is 51.2 Pa? [Surface tension of soap solution = 3.2 × 10−2 N/m]
State dimension of potential gradient.
Three identical cells each of emf 'e' are connected in parallel to form a battery. What is the emf of the battery?
In a potentiometer, a cell is balanced against 110 cm when the circuit is open. A cell is balanced at 100 cm when short-circuited through a resistance of 10 Ω. Find the internal resistance of the cell.
