Potentiometer

Q.

The potential energy of a particle in a force field is $U=\frac{A}{r^2}-\frac{B}{r}$ where A and B are positive constants and r is the distance of particle from the centre of the field For stable equilibrium the distance of the particle is

1)A/B

2)B/A

3)B/2A

4)2A/B

Q. Precision in measurement depends on(1) Zero error(2) Parallax(3) Least count of instrument(4) Calibration of instrument34.In an experiment to measure the diameter of a wire

Q. Why distance is always positive or zero?

Q.

What is a type B potentiometer?

Q. In a certain field, the potential energy is U= axbx, where a and b constants. The particle is in stableequilibrium at x equal to(1) Zero(2)3b2a(4)2a(E)3b

Q. A battery with negligible internal resistance is connected with 10m long wire. A standard cell gets balanced on 600 cm length of this wire. On increasing the length of potentiometer wire by 2m, the null point will be displaced by,

1. 200 cm
2. 120 cm
3. 720 cm
4. 600 cm

Q. Four metal plates numbered $1,2,3$ and $4$ are arranged as shown below. The area of each plate is $A$ and separation between adjacent plates is $d$. The capacitance of the arrangement is

1. $\frac{{\epsilon }_{o}A}{d}$
2. $\frac{3{\epsilon }_{o}A}{d}$
3. $\frac{4{\epsilon }_{o}A}{d}$
4. $\frac{2{\epsilon }_{o}A}{d}$

Q. A wire has a non-uniform cross-section as shown in figure. A steady current flows through it. The drift speed of electrons at point $\text{P}$ and $\text{Q}$ is $v_P$ and $v_Q$.

1. Data insufficient
2. $v_P=v_Q$
3. $v_P>v_Q$
4. $v_P<v_Q$

Q. In an experiment to measure the internal resistance of a cell by a potentiometer, it is found that the balance point is at a length of $2\text{m}$, when the cell is shunted by a $5\Omega$ resistance and at a length of $3\text{m}$, when the cell is shunted by a $10\Omega$ resistance. The internal resistance of the cell is

1. $1.5\Omega$
2. $10\Omega$
3. $15\Omega$
4. $1\Omega$

Q. Two cells of emfs $E_1$ and $E_2(E_1>E_2)$ are connected as shown in fig.


When a potentiometer is connected between $A$ and $B$, the balancing length of the potentiometer wire is $300\text{cm}$. On connecting the same potentiometer between $A$ and $C$, the balancing length is $100\text{cm}$. The ratio $\frac{E_1}{E_2}$ is

1. $3:1$
2. $1:3$
3. $2:3$
4. $3:2$

Q. In an experiment to measure the internal resistance of a cell by potentiometer, it is found that the balance point is at a length of 2 m when the cell is shunted by a $5\Omega$ resistance; and is at a length of 3 m when the cell is shunted by a $10\Omega$ resistance. The internal resistance of the cell is, then

1. $1.5\Omega$
2. $10\Omega$
3. $15\Omega$
4. $1\Omega$

Q. The circuit shown here is used to compare the e.m.f.'s of the cells $E_1$ and $E_2(E_1>E_2)$. When the galvanometer is connected to $E_1$, the null point is at $C$. When the galvanometer is connected to $E_2$, the null point will be

1. to the left of $C$
2. to the right of $C$
3. at $C$ itself
4. no where on $AB$

Q. The potentiometer works on the principle that at constant temperature, the resistance of a wire is proportional to its

1. Length
2. Area of cross section
3. Material density
4. None of the above

Q. A cell is connected in the secondary circuit of a potentiometer and a balance point is obtained at 84 cm When the cell is shunted by a $5\Omega$ resistor, the balance point changes to 70 cm. If the $5\Omega$ resistor is replaced with $3\Omega$ resistor then the balance point will be at

1. 53 cm
2. 63 cm
3. 42 cm
4. 112 cm

Q. A wire has a non-uniform cross-section as shown in figure. A steady current flows through it. The drift speed of electrons at point $\text{P}$ and $\text{Q}$ is $v_P$ and $v_Q$.

1. $v_P<v_Q$
2. $v_P=v_Q$
3. $v_P>v_Q$
4. Data insufficient

Q. why should venturi meter should use only pipe

Q. If a cell of internal resistance $1.5\Omega$ and emf of $1.5V$ balances $500cm$ on a potentiometer wire, now by what length would the balance point shift if a cell of internal resistance $2\Omega$ and emf of $2V$ is connected in parallel (along the same polarity) with the prior cell?

1. $71.4cm$ towards left
2. $71.4cm$ towards right
3. $125cm$ towards right
4. Does not shift

Q. Potentiometer wire is $100\text{cm}$ long and a constant potential difference is maintaned across it. Two cells are connected in series first to support one another and then in opposite direction. The balance points are obtained at $50\text{cm}$ and $10\text{cm}$ from the positive end of the wire in the two cases. The ratio of emf's is:

1. $5:1$
2. $5:4$
3. $3:4$
4. $3:2$

Q.

In the potentiometer circuit shown in figure the internal resistance of the 6 V battery is 1 ohm and the length of the wire AB is 100 cm. When AD = 60 cm the galvanometer shows no deflection. The emf of cell C is (the resistance of wire AB is 2 ohm)

1. 0.7 V

2. 0.8 V

3. 0.9 V

4. 1 V

Q. If a voltmeter draws zero current from the circuit then it is a potentiometer.

1. False
2. True

Q. potential function under conservative is given as U=2xy-yz^2. Find Force at xy-yz^2. SOLVE IN DETAIL

Q. For comparing the e.m.f.'s of two cells with a potentiometer, a standard cell is used to develop a potential gradient along the wires. Which of the following possibilities would make the experiment unsuccessful.

1. The e.m.f. of the standard cell is larger than the E e.m.f.'s of the two cells
2. The diameter of the wires is the same and uniform throughout
3. The number of wires is ten
4. The e.m.f. of the standard cell is smaller than the e.m.f.'s of the two cells

Q. A cylindrical tube of length $l$ has inner radius $a$ while outer radius $b$. The resistance of the tube between its inner and outer surfaces will be
$($resistivity of material is $\rho )$

1. $\ln \left(\frac{b^2}{a}\right)$
2. $\frac{\rho }{2\pi l}\ln \frac{b}{a}$
3. $\frac{\rho }{2\pi b}\ln a$
4. $\frac{{\ln }^2\left(a/b\right)}{2\pi l}$

Q. The maximum potential difference that can be detected by a potentiometer is the potential drop across the potentiometer wire.

1. False
2. True

Q. $AB$ is a potentiometer wire of length $100\text{cm}$ and its resistance is $10\Omega$. It is connected in series with a resistance $R=40\Omega$ and a battery of emf $2\text{V}$ and negligible internal resistance. If a source of unknown emf $E$ is balanced by $40\text{cm}$ length of the potentiometer wire, then the value of $E$ is

1. $0.8\text{V}$
2. $1.6\text{V}$
3. $0.08\text{V}$
4. $0.16\text{V}$

Q. A potentiometer wire of length 1 m and resistance $10\Omega$ is connected in series with a cell of e.m.f 2 volt with internal resistance $1\Omega$ and a resistance box including a resistance R. If the potential difference between the ends of the wire is 1 mV, then the value of R will be

1. $9989\Omega$
2. $10000\Omega$
3. $19989\Omega$
4. $20000\Omega$

Q. A daniel cell is balanced on 125 cm length of a potentiometer wire. When the cell is short circuited with a $2\Omega$ resistance, the balancing length obtained is 100 cm. Internal resistance of the cell will be

1. $1.5\Omega$
2. $0.5\Omega$
3. $1.25\Omega$
4. $\frac{4}{5}\Omega$

Q. In the following circuit the potential difference between the points B and C is balanced against 40 cm length of potentiometer wire. In order to balance the potential difference between the points C and D, where should jockey be pressed

1. 32 cm
2. 16 cm
3. 8 cm
4. 4 cm

Q. A cylindrical tube of length $l$ has inner radius $a$ while outer radius $b$. The resistance of the tube between its inner and outer surfaces will be
$($resistivity of material is $\rho )$

1. $\frac{\rho }{2\pi l}\ln \frac{b}{a}$
2. $\frac{\rho }{2\pi b}\ln a$
3. $\frac{{\ln }^2\left(a/b\right)}{2\pi l}$
4. $\ln \left(\frac{b^2}{a}\right)$

Q. A potentiometer wire is 100 cm long and a constant p.d. is maintained across it. Two cells A and B are connected in series first and then in opposition. The balance points were obtained at 50 cm and 30 cm. Find the ratio of the e.m.f.s of the cells.

1. 1:2
2. 3:2
3. 4:1
4. 3:5