WBJEE · Physics · Current Electricity
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
- A \(v_{d}\)
- B \(2 v_{d}\)
- C \(v_{d} / 2\)
- D \(v_{d} / 4\)
Answer & Solution
Correct Answer
(C) \(v_{d} / 2\)
Step-by-step Solution
Detailed explanation
The drift velocity is given as \[ \begin{aligned} v_{d} &=\frac{i}{n e A}=\frac{E}{R \times n e A} \\ &=\frac{E \times A}{\rho l \times n e A}=\frac{E}{ln e} \end{aligned} \] When length of wire changed to 2l , the new drift velocity.…
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