Find the mobility of an electron in a wire if its average collision time is $9.1 \times 10^{-15} \,s$. (Charge of electron $= 1.6 \times 10^{-19} \,C$ and mass of electron $= 9.1 \times 10^{-31} \,kg$)

Consider a metallic cube of edge length $L$. Its resistance,$R$,measured across its opposite faces is $R = \frac{m_e v}{n e^2 L^2}$,where $n$ is the number density and $v$ is the drift speed of electrons in the cube,and $e$ and $m_e$ are the charge and mass of an electron respectively. Assuming the de-Broglie wavelength of the electron to be $L$,the maximum resistance of the sample is closest to ............. $\Omega$ ($e = 1.60 \times 10^{-19} \, C$; $m_e = 9.11 \times 10^{-31} \, kg$; Planck's constant,$h = 6.63 \times 10^{-34} \, Js$)

On increasing the temperature of a conductor,its resistance increases because

$A$ potential difference $V$ is applied across the ends of a copper wire of diameter $d$ and length $L$. If only the diameter $d$ is doubled,the drift velocity becomes:

$A$ current of $10\, A$ exists in a wire of cross-sectional area of $5\, mm^{2}$ with a drift velocity of $2 \times 10^{-3}\, m/s$. The number of free electrons in each cubic meter of the wire is ..........

The total momentum of electrons in a straight wire of copper of length $1\, m$ carrying a current of $16\, A$ is