A potentiometer has uniform potential gradient across it. Two cells connected in series $(i)$ to support each other and $(ii)$ to oppose each other are balanced over $6\,m$ and $2\,m$ respectively on the potentiometer wire. The $e.m.f.$’s of the cells are in the ratio of
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A uniform metallic wire carries a current $2\,A$. when $3.4\,V$ battery is connected across it. The mass of uniform metallic wire is $8.92 \times 10^{-3} \,kg$. density is $8.92 \times 10^3\,kg / m ^3$ and resistivity is $1.7 \times 10^{-8} \Omega- m$. The length of wire is $l=............\,m$
The current $i_1$ and $i_2$ through the resistors $R_1(=10\,\Omega )$ and ${R_2}\left( { = 30\,\Omega } \right)$ in the circuit diagram with $E_1 = 3\,V$, $E_2 = 3\,V$ and $E_3 = 2\,V$ are respectively
A torch bulb rated as $4.5\, W$, $1.5\, V$ is connected as shown in the figure. The $e.m.f.$ of the cell needed to make the bulb glow at full intensity is ................ $V$
In the given potentiometer circuit length of the wire $AB$ is $3\,m$ and resistance is $R=4.5\,\Omega $. The length $AC$ for no deflection in galvanometer is ............... $m$
Four wires of equal length and of resistances $10$ $ ohms$ each are connected in the form of a square. The equivalent resistance between two opposite corners of the square is ............. $ohm$
In order to measure the internal resistance $r_1$ of a cell of emf $E$, a meter bridge of wire resistance $R_0=50 \Omega$, a resistance $R_0 / 2$, another cell of emf $E / 2$ (internal resistance $r$ ) and a galvanometer $G$ are used in a circuit, as shown in the figure. If the null point is found at $l=72 cm$, then the value of $r_1=$ . . . . $\Omega$
The $V-i$ graph for a conductor makes an angle $\theta $ with $V-$ axis. Here $ V$ denotes the voltage and $i$ denotes current. The resistance of conductor is given by