A current of $1.6\, A$ is flowing through a wire having cross-sectional area $1\, mm^2$. If density of free electrons in the material of the wire is $10^{29}\, per\, m^3$, the drift velocity of electrons will be
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$A$ battery of $\mathrm{emf}$ $E$ and internal resistance $r$ is connected across a resistance $R$. Resistance $R$ can be adjusted to any value greater than or equal to zero. Agraph is plotted between the current $(i)$ passing through the resistance and potential difference $(V) $ across it. Select the correct alternative $(s)$.
A potentiometer wire has length $10\, m$ and resistance $20\,\Omega $. A $2. 5\, V$ battery of negligible internal resistance is connected across the wire with an $80\,\Omega $ series resistance. The potential gradient on the wire will be
In India electricity is supplied for domestic use at $220 \,V$. It is supplied at $110 \,V$ in USA. If the resistance of a $60 \,W$ bulb for use in India is $R$, the resistance of a $60 \,W$ bulb for use in USA will be
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 ........... $m$
You are given several identical resistances each of value $R = 10\,\Omega $ and each capable of carrying maximum current of $1\, ampere$. It is required to make a suitable combination of these resistances to produce a resistance of $5\,\Omega $ which can carry a current of $4\, amperes$. The minimum number of resistances of the type $R$ that will be required for this job