Distance as well as power is scalar quantity.
Current density $\vec{J}=\frac{I}{A} \hat{n}$, is a vector quantity.
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For comparing the $e.m.f.$'s of two cells with a potentiometer, a standard cell is used to develop a potential gradient along the wires. Which of the following possibilities would make the experiment unsuccessful
Suppose a current carrying wire has a cross-sectional area that, gradually become smaller along the wire, has the shape of a very long cone as shown in figure. Choose the correct statement
The resistance of a $5\, cm$ long wire is $10\, \Omega$. It is uniformly stretched so that its length becomes $20\, cm$. The resistance of the wire is ............. $\Omega$
As shown in the figure, a network of resistors is connected to a battery of $2\,V$ with an internal resistance of $3\,\Omega$. The currents through the resistors $R_4$ and $R_5$ are $I_4$ and $I_5$ respectively. The values of $I_4$ and $I_5$ are :
A primary cell has an $e.m.f.$ of $1.5\,volts$, when short-circuited it gives a current of $3$ amperes. The internal resistance of the cell is .............. $ohm$
A wire $100\,cm$ long and $2.0\,mm$ diameter has a resistance of $0.7\, ohm$, the electrical resistivity of the material is ...........$ \times {10^{ - 6}}\,ohm \times m$