A piece of copper and another of germanium are cooled from room temperature to $80\, K$. The resistance of :-
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Copper is metal and germanius is semiconductor. Resistance of a metal decreases and that of a semiconductor increases with decrease in tempertaure.
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Three resistances of magnitude $2$, $3$ and $5$ $ohm$ are connected in parallel to a battery of $10\, volts$ and of negligible resistance. The potential difference across $3\,\Omega $ resistance will be ............... $volts$
In the given circuit, an ideal voltmeter connected across the $10\,\Omega $ resistance reads $2\, V$. The internal resistance $r$, of each cell is ................... $\Omega$
In the circuit shown below (on the left) the resistance and the emf source are both variable. The graph of seven readings of the voltmeter and the ammeter ( $V$ and $I$, respectively) for different settings of resistance and the emf, taken at equal intervals of time $\Delta t$, are shown below (on the right) by the dots connected by the curve $E F G H$. Consider the internal resistance of the battery to be negligible and the voltmeter an ammeter to be ideal devices. (Take, $R_0 \equiv \frac{V_0}{I_0}$ ).
Then, the plot of the resistance as a function of time corresponding to the curve $E F G H$ is given by
A wire of diameter $0.02\,meter$ contains $10^{28}$ free electrons per cubic meter. For an electrical current of $100\, A$, the drift velocity of the free electrons in the wire is nearly