(D) Given: Length $l = 1 \,m$,Area $A = 5 \times 10^{-7} \,m^{2}$,Current $I = 1 \,A$,Electron density $n = 8 \times 10^{28} \,m^{-3}$,Charge of elect

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(D) Given: Length $l = 1 \,m$,Area $A = 5 \times 10^{-7} \,m^{2}$,Current $I = 1 \,A$,Electron density $n = 8 \times 10^{28} \,m^{-3}$,Charge of electron $e = 1.6 \times 10^{-19} \,C$. The drift velocity $v_{d}$ is given by the formula $v_{d} = \frac{I}{neA}$. Substituting the values: $v_{d} = \frac{1}{8 \times 10^{28} \times 1.6 \times 10^{-19} \times 5 \times 10^{-7}} = \frac{1}{64 \times 10^{2}} = \frac{1}{6.4 \times 10^{3}} \,m/s$. The time $T$ taken to drift across the length $l$ is $T = \frac{l}{v_{d}}$. $T = \frac{1}{1 / (6.4 \times 10^{3})} = 6.4 \times 10^{3} \,s$.

Class 12 Physics Current Electricity Current Density, Drift Velocity and Mobility

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$A$ copper wire of length $1 \,m$ and uniform cross-sectional area $5 \times 10^{-7} \,m^{2}$ carries a current of $1 \,A$. Assuming that there are $8 \times 10^{28}$ free electrons per $m^{3}$ in copper,how long will an electron take to drift from one end of the wire to the other?

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A
$0.8 \times 10^{3} \,s$
B
$1.6 \times 10^{3} \,s$
C
$3.2 \times 10^{3} \,s$
D
$6.4 \times 10^{3} \,s$

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Current Electricity

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Current Density, Drift Velocity and Mobility

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Rod	Length,Diameter,Potential Difference
$(A)$	$L, 3d, V$
$(B)$	$2L, d, 2V$
$(C)$	$3L, 2d, 2V$

$A$ copper wire of length $1 \,m$ and uniform cross-sectional area $5 \times 10^{-7} \,m^{2}$ carries a current of $1 \,A$. Assuming that there are $8 \times 10^{28}$ free electrons per $m^{3}$ in copper,how long will an electron take to drift from one end of the wire to the other?

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$A$ copper wire has a square cross-section,$2.0 \, mm$ on a side. It carries a current of $8 \, A$ and the density of free electrons is $8 \times 10^{28} \, m^{-3}$. The drift speed of electrons is equal to

Two identical conductors are kept at the same temperature. If the ratio of the potential difference across them is $1 : 2$,what will be the ratio of their drift velocities?

$A$ copper wire of length $1 \ m$ and radius $1 \ mm$ is connected in series with an iron wire of length $2 \ m$ and radius $3 \ mm$. If a current flows through both wires,the ratio of the current density in the copper wire to that in the iron wire will be:

Three copper rods are subjected to different potential differences. Compare the drift speed of electrons through them. Assume that all $3$ are at the same temperature.RodLength,Diameter,Potential Difference$(A)$$L, 3d, V$$(B)$$2L, d, 2V$$(C)$$3L, 2d, 2V$

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Three copper rods are subjected to different potential differences. Compare the drift speed of electrons through them. Assume that all $3$ are at the same temperature.
Rod Length,Diameter,Potential Difference
$(A)$ $L, 3d, V$
$(B)$ $2L, d, 2V$
$(C)$ $3L, 2d, 2V$