A $1\,m$ long copper wire carries a current of $1\,A$. If the cross section of the wire is $2.0\,mm ^{2}$ and the resistivity of copper is $1.7 \times 10^{-8}\,\Omega\,m$. the force experienced by moving electron in the wire is $\times 10^{-23}\,N$. (charge on electron $=1.6 \times 10^{-19}\,C$ )
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In a meter bridge, the null point is found at a distance of $25\, cm$ from $A$. If now a resistance of $10\,\Omega $ is connected in parallel with $S$, the null point occurs at mid point of $AB$. The value of $R$ is ................. $\Omega$
Four wires of the same diameter are connected in turn between two points, maintained at a constant potential difference. Their resistivities are; $\rho $ and $L$ (wire $1$ )., $1.2\,\rho $ and $1.2\,L$ (wire $2$ ), $0.9\,\rho $ and $0.9\,L$ (wire $3$ ) and $\rho $ and $1.5\,L$ (wire $4$ ). Rank the wires according to the rates at which energy is dissipated as heat, greatest first
If $n,\,e,\,\tau $ and $m$ respectively represent the density, charge relaxation time and mass of the electron, then the resistance of a wire of length $l$ and area of cross-section $A$ will be
A coil develops heat of $800\, cal/sec$. When $20\, volts$ is applied across its ends. The resistance of the coil is .............. $\Omega$ ($1$ $cal$ = $4.2$ $joule$)
If a wire of resistance $20\,\Omega $ is covered with ice and a voltage of $210\, V$ is applied across the wire, then the rate of melting of ice is .................. $g/s$
The drift velocity of free electrons in a conductor is ‘$v$’ when a current ‘$i$’ is flowing in it. If both the radius and current are doubled, then drift velocity will be