A current of $10 \,A$ is maintained in a conductor of cross-section $1 \,cm ^2$. If the number density of free electrons be $9 \times 10^{28} \,m ^{-3}$, the drift velocity of free electrons is .......... $m / s$
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A uniform wire of length $l$ and radius $r$ has a resistance of $100\, \Omega $. It is recast into a wire of radius $\frac{r}{2}$. The resistance of new wire will be ............... $\Omega$
In the circuit shown, the cell is ideal, with $emf$ $=$ $15$ $V$. Each resistance is of $3 $ $\Omega$ . The potential difference across the capacitor is.....$V$
A copper wire of length $1\, m$ and radius $1\, mm$ is joined in series with an iron wire of length $2\, m$ and radius $3\, mm$ and a current is passed through the wires. The ratio of the current density in the copper and iron wires is
Consider the circuit given here with the following parameters $E.M.F.$ of the cell = $12\, V$. Internal resistance of the cell $ = 2\,\Omega $. Resistance $R = 4\,\Omega $ Which one of the following statements in true
The four arms of a Wheatstone bridge have resistances as shown in the figure. A galvanometer of $15\, \Omega$ resistance is connected across $BD$. Calculate the current through the galvanometer when a potential difference of $10\, V$ is maintained across $AC.$
In the circuit shown, the current through the $4\,\Omega $ resistor is $1\, amp$ when the points $P$ and $M$ are connected to a d.c. voltage source. The potential difference between the points $M$ and $N$ is ............... $volt$
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 $r_1=$ . . . . $\Omega$