Tend identical cells each of potential $E$ and internal resistance $r$ are connected in series to form a closed circuit. An ideal voltmeter connected across three cells, will read $...........E$
AIIMS 2016, Medium
Download our app for free and get started
(b)
Given: Initial number of cells $\left(n_1\right)=10$;
Potential of each cell $=E$; Internal resistance of each cell $=r$ and final number of cells $\left(n_2\right)=3$
We know from the Ohm's law, total voltage of ten cells $=10 \times E=10 E$ and total resistance in ten cells $=10 \times r$ $=10\,r$
Therefore current in the circuit $(I)=\frac{10 E}{10 r}=\frac{E}{r}$ or potential difference across three cells $=I \times 3 r=\frac{E}{r} \times 3 r=3\,E$
(Since the voltmeter is ideal, therefore it will read $3E$ ).
Download our appand get started for free
Experience the future of education. Simply download our apps or reach out to us for more information. Let's shape the future of learning together!No signup needed.*
Similar Questions
- 1If you are provided three resistances $2 \,\Omega$, $3 \,\Omega$ and $6 \,\Omega$. How will you connect them so as to obtain the equivalent resistance of $4 \,\Omega$View Solution
- 2A wire $50\, cm$ long and $1\;mm^2$ in cross -section carries a current of $4\; A$ when connected to a $2\; V$ battery. The resistivity of the wire isView Solution
- 3$A$ wire of length $L$ and $3$ identical cells of negligible internal resistances are connected in series. Due to the current, the temperature of the wire is raised by $\Delta T$ in time $t. N$ number of similar cells is now connected in series with a wire of the same material and cross section but of length $2L$. The temperature of the wire is raised by the same amount $\Delta T$ in the same time $t$. The value of $N$ is :View Solution
- 4Two resistance wires on joining in parallel the resultant resistance is $\frac{6}{5}\,ohms$. One of the wire breaks, the effective resistance is $2\,ohms$. The resistance of the broken wire is ............ $ohm$View Solution
- 5In a meter bridge experiment, resistances are connected as shown in the following figure. The balancing length $l_1$ is $55\, cm$. Now, an unknown resistance $x$ is connected in series with $P$ and the new balancing length is found to be $75\, cm$. The value of $x$ isView Solution
- 6In a potentiometer (see figure) a balance is obtained at a length of $400\ mm$ when using a known battery of emf $1.6\ V$. After removing this battery, another battery of unknown emf is used and balance is obtained at a length of $650\ mm.$ The emf of unknown battery is ............. $volt$View Solution
- 7In the circuit diagram shown in figure given below, the current flowing through resistance $3\, \Omega$ is $\frac{ x }{3}\,A$. The value of $x$ is $...........$View Solution
- 8Consider a thin square sheet of side $\mathrm{L}$ and thickness $\mathrm{t}$, made of a material of resistivity $\rho$. The resistance between two opposite faces, shown by the shaded areas in the figure isView Solution
- 9Three resistors of $4\,\Omega ,6\,\Omega $ and $12\,\Omega $ are connected in parallel and the combination is connected in series with a $1.5\, V$ battery of $1\,\Omega $ internal resistance. The rate of Joule heating in the $4\,\Omega $ resistor is ................ $W$View Solution
- 10In 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 ................ $\Omega $View Solution