UPSEE 2019 Solved Paper

As we know that the current entering in a conductor is equal to the current leaving the conductor. Which is based on the conservation of the charge.
As, drift velocity of electrons,
vd=

eEτ

m

⇒vd∝E
Where, e= charge of electron, τ= relaxation time and m= mass of electron and E= electric field inside a conductor.
Since, drift velocity depends on the electric field inside a conductor, so it varies with change in cross-section of conductor.
Hence, only current is constant in such conductor.