An electric cell of emf E is connected across a copper wire of diameter d and length l . The drift velocity of electrons in the wire is v d . If the length of the wire is changed to 2 l , the new dr

Question

An electric cell of emf E is connected across a copper wire of diameter d and length l . The drift velocity of electrons in the wire is v d ​ . If the length of the wire is changed to 2 l , the new drift velocity of electrons in the copper wire will be

TestHub · Accepted Answer

The drift velocity is given as v d ​ ​ = n e A i ​ = R × n e A E ​ = ρl × n e A E × A ​ = l n e E ​ ​ When length of wire changed to 2l , the new drift velocity. v d ′ ​ ∴ ⇒ v d ′ ​ ​ = ρ × 2 l × n e E ​ v d ​ v d ′ ​ ​ = E / ρ lne E / ρ 2 lne ​ = 2 1 ​ = 2 v d ​ ​ ​

Physics - Current Electricity Question with Solution | TestHub

Options:

Doubts & Discussion