The resistivity of a potentiometer wire is $40 \times {10^{ - 8}}\,ohm - m$ and its area of cross-section is $8 \times {10^{ - 6}}\,{m^2}$. If $0.2\, amp$ current is flowing through the wire, the potential gradient will be
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If three resistors of resistance $2 \,\Omega$, $4 \,\Omega$ and $5 \,\Omega$ are connected in parallel then the total resistance of the combination will be
$A$ total charge $Q$ flows across a resistor $R$ during a time interval $= T$ in such a way that the current vs. time graph for $0 \rightarrow T$ is like the loop of a sin curve in the range $0 \rightarrow \pi$ . The total heat generated in the resistor is
Electric bulb $50\, W$ - $100\, V$ glowing at full power are to be used in parallel with battery $120\, V$, $10 \,\Omega$. Maximum number of bulbs that can be connected so that they glow in full power is
A current of two amperes is flowing through a cell of $e.m.f.$ $5\, volts$ and internal resistance $0.5\, ohm$ from negative to positive electrode. If the potential of negative electrode is $10\,V$, the potential of positive electrode will be .............. $V$
A wire of resistance $R$ and radius $r$ is stretched till its radius became $r / 2$. If new resistance of the stretched wire is $x R$, then value of $x$ is $\qquad$
For a cell terminal $P.D.$ is $2.2\;V$ when circuit is open and reduces to $1.8\;V$ when cell is connected to a resistance of $R = 5\,\Omega $. Determine internal resistance of cell $(r)$ is then ........ $\Omega$
An insulating pipe of cross-section area $'A'$ contains an electrolyte which has two types of ions $\rightarrow$ their charges being $-e$ and $+2e$. $A$ potential difference applied between the ends of the pipe result in the drifting of the two types of ions, having drift speed $= v$ ($-ve$ ion) and $v/4$ ($+ve$ ion). Both ions have the same number per unit volume $= n$. The current flowing through the pipe is
Consider the circuits shown in the figure. Both the circuits are taking same current from battery but current through $R$ in the second circuit is $\frac{1}{{10}}$$^{th}$ of current through $R$ in the first circuit. If $R$ is $11$ $\Omega$, the value of $ R_1$ ................ $\Omega$