Two identical cells send the same current in $2\,\Omega $ resistance, whether connected in series or in parallel. The internal resistance of the cell should be ............... $\Omega$
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The temperature coefficient of resistance of tungsten is $4.5 \times 10^{-3}{ }^{\circ} C ^{-1}$ and that of germanium is $-5 \times 10^{-2}{ }^{\circ} C ^{-1}$. A tungsten wire of resistance $100 \,\Omega$ is connected in series with a germanium wire of resistance $R$. The value of $R$ for which the resistance of combination does not change with temperature is .......... $\Omega$
A $10 \,m$ long potentiometer wire is connected to a battery having a steady voltage. A Leclanche cell is balanced at $4 \,m$ length of the wire. If the length is kept the same, but its cross-section is doubled, the null point will be obtained at ........... $m$
The resistance of a wire is $5\,ohm$ at $50\,^o C$ and $6\,ohm $ at $100\,^o C$. The resistance of the wire at $0\,^o C$ will be .............. $\Omega$
Four wires of the same diameter are connected in turn between two points, maintained at a constant potential difference. Their resistivities are; $\rho $ and $L$ (wire $1$ )., $1.2\,\rho $ and $1.2\,L$ (wire $2$ ), $0.9\,\rho $ and $0.9\,L$ (wire $3$ ) and $\rho $ and $1.5\,L$ (wire $4$ ). Rank the wires according to the rates at which energy is dissipated as heat, greatest first
A voltmeter having a resistance of $998\, ohms$ is connected to a cell of $e.m.f.$ $2\, volt$ and internal resistance $2\, ohm$. The error in the measurement of $e.m.f.$ will be
A resistor develops $500\, J$ of thermal energy in $20 \,s$ when a current of $1.5\, A$ is passed through it. If the current is increased from $1.5 \,A$ to $3\, A$ what will be the energy (in $J$) developed in $20\, s$.