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# A steady current flows in a metallic conductor of non-uniform cross-section. The quantity/quantities constant along the length of the conductor are

$\begin {array} {1 1} (A)\;Current, \: electric \: field \: and \:drift\: speed. & \quad (B)\;Drift\: speed\: only \\ (C)\;Current\: and\: drift\: speed\: only & \quad (D)\;Current\: only \end {array}$

Can you answer this question?

Steady current implies current is uniform across the cross-section.
Since current is constant, current per unit area and hence drift velocity are not constant.
$J = nev_d = \sigma E$
The above relation shows that nothing apart from the current is constant.
Ans : (D)
answered Feb 8, 2014
edited Mar 14, 2014