A capacitor is connected to a cell of $emf$ $E$ having some internal resistance $r$. The potential difference across the
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(b) In the given case cell is in open circuit $(i = 0)$ so voltage across the cell is equal to its $e.m.f.$
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In an electric circuit, a cell of certain emf provides a potential difference of $1.25\, {V}$ across a load resistance of $5\, \Omega .$ However, it provides a potential difference of $1\, {V}$ across a load resistance of $2\, \Omega$. The $emf$ of the cell is given by $\frac{x}{10} v$. Then the value of $x$ is ..... .
The length of a metallic wire is increased by $20 \%$ and its area of cross section is reduced by $4 \%$. The percentage change in resistance of the metallic wire is $.......$
At room temperature $\left(27^{\circ} \mathrm{C}\right)$, the resistance of a heating element is $50 \Omega$. The temperature coefficient of the material is $2.4 \times 10^{-4}{ }^{\circ} \mathrm{C}^1$. The temperature of the element, when its resistance is $62 \Omega$, is $\qquad$ ${ }^{\circ} \mathrm{C}$.
A $1\,m$ long wire is broken into two unequal parts $X$ and $Y$ The $X$ part of the wire is streched into another wire $W$. Length of $W$ is twice the length of $X$ and the resistance of $W$ is twice that of $Y$. Find the ratio of length of $X$ and $Y$.
A battery is connected to a uniform resistance wire $AB$ and $B$ is earthed. Which one of the graphs below shows how the current density $J$ varies along $AB$