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JEE Physics

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Chapter 33

Experiment - Potentiometer - all with Video Answers

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Chapter Questions

01:15

Problem 2860

A $10 \mathrm{~m}$ wire potentiometer is connected to an accumulator of steady voltage. A $7.8 \mathrm{~m}$ length of it balances the emf of a cell on 'open-circuit'. When cell delivers current through a conductor of resistance $10 \Omega$ it is balanced against $7.0 \mathrm{~m}$ of the same potentiometer. What is the internal resistance of the cell ?
(A) $1.24 \Omega$
(B) $1.36 \Omega$
(C) $1.14 \Omega$
(D) $1 \Omega$

Prem Bijarniya
Prem Bijarniya
Numerade Educator
01:57

Problem 2861

A potentiometer is preferred over a voltmeter to measure the emf of a cell because...
(A) The material of the potentiometer wire has a low temperature coefficient of resistance.
(B) emf measured by potentiometer is more accurate because the cell is open-circuit.
(C) potential gradients can be varied in a potentiometer using a rheostat.
(D) Potentiometer is more sensitive than voltmeter.

Prem Bijarniya
Prem Bijarniya
Numerade Educator
01:48

Problem 2862

Circuit for the measurement of resistance by potentiometer is shown. The galvanometer is first connected at point $\mathrm{A}$ and zero-deflection is observed at length $\mathrm{PJ}=10 \mathrm{~cm} .$ In the second case, it is connected at a point $\mathrm{C}$ and zero deflection is observed at a length $30 \mathrm{~cm}$ from $\mathrm{P}$. Then what is the unknown resistance $\mathrm{X}$ ?
(A) $(\mathrm{R} / 2)$
(B) $(\mathrm{R} / 3)$
(C) $2 \mathrm{R}$
(D) $3 \mathrm{R}$

Prem Bijarniya
Prem Bijarniya
Numerade Educator
02:59

Problem 2863

Consider the potentiometer circuit shown. The potentiometer wire is $600 \mathrm{~cm}$ long and having resistance $15 \mathrm{r}$. At what distance from the point A should the jockey touch the wire to get zero deflection in the galvanometer?
(A) $450 \mathrm{~cm}$
(B) $320 \mathrm{~cm}$
(C) $420 \mathrm{~cm}$
(D) $360 \mathrm{~cm}$

Prem Bijarniya
Prem Bijarniya
Numerade Educator
01:12

Problem 2864

In the experiment of potentiometer wire $\mathrm{AB}$ is $100 \mathrm{~cm}$ long shown in figure When $\mathrm{AC}=40 \mathrm{~cm}$, no deflection occurs in the galvanometer. What is the value of $R$ ?
(A) $15 \Omega$
(B) $18 \Omega$
(C) $12 \Omega$
(D) $14 \Omega$

Prem Bijarniya
Prem Bijarniya
Numerade Educator
01:15

Problem 2865

If the deflection of the galvanometer is in the same direction at both the ends of the potential meter wire, then point out the statement which is definitely not the possible reason for the.
(A) current flows is the same direction in both cases through the galvanometer.
(B) Connecting wire in the galvanometer circuit is broken.
(C) The positive terminals of all the cells are not connected at one point.
(D) The potential difference between the ends of the wire is less than the emf of the cell which is to be measured.

Prem Bijarniya
Prem Bijarniya
Numerade Educator
02:26

Problem 2866

In experiment of the potentiometer wire $\mathrm{AB}$ of length $100 \mathrm{~cm}$ has a resistance of $10 \Omega$. It is connected in series with a resistance $\mathrm{R}$ and a cell of emf 2 volts and of negligible internal resistance. A source emf $10 \mathrm{mV}$ is balanced against a length of $40 \mathrm{~cm}$ of the potentiometer wire. What is the value of the external resistance?
(A) $900 \Omega$
(B) $820 \Omega$
(C) $790 \Omega$
(D) $670 \Omega$

Prem Bijarniya
Prem Bijarniya
Numerade Educator
01:10

Problem 2867

A potentiometer wire, which is $4 \mathrm{~m}$ long is connected to the terminals of a battery of steady voltage. A leclanche cell gives a null point at $1 \mathrm{~m}$ if the length of the potentiometer wire be increased by $1 \mathrm{~m}$, What is the new position of the null point?
(A) $1.25 \mathrm{~m}$
(B) $1.4 \mathrm{~m}$
(C) $1.75 \mathrm{~m}$
(D) $1.2 \mathrm{~m}$

Prem Bijarniya
Prem Bijarniya
Numerade Educator
01:25

Problem 2868

A battery of $2 \mathrm{~V}$ and internal resistance 1 is used to send a current through a potentiometer wire of length $200 \mathrm{~cm}$ and resistance $4 \mathrm{Q}$ What is the potential gradient of the wire?
(A) $8 \times 10^{-3} \mathrm{~V} \mathrm{~cm}^{-1}$
(B) $4 \times 10^{-3} \mathrm{~V} \mathrm{~cm}^{-1}$
(C) $6 \times 10^{-3} \mathrm{~V} \mathrm{~cm}^{-1}$
(D) $2 \times 10^{-3} \mathrm{~V} \mathrm{~cm}^{-1}$

Prem Bijarniya
Prem Bijarniya
Numerade Educator