Search any question & find its solution
Question:
Answered & Verified by Expert
A metal wire is subjected to a constant potential difference. When the temperature of the metal wire increases, the drift velocity of the electron in it
Options:
Solution:
2458 Upvotes
Verified Answer
The correct answer is:
decreases, thermal velocity of the electron increases
Drift velocity of the electron is given as
$$
v_{d}=\frac{e E \tau}{m}
$$
where, $e=$ charge on electron,
$E=$ electric field,
$\tau=$ relaxation time
and $m=$ mass of the electron.
Since,
$$
\therefore \quad v_{d}=\frac{e V \tau}{m l}
$$
Since, $e, V, m$ and $l$ are constant .
$$
\therefore \quad v_{d} \propto \tau
$$
On increasing the temperature of metal wire, relaxation time decreases, therefore drift velocity of electrons also decreases.
But on increasing temperature of metal wire, thermal velocity of electron increases.
$$
v_{d}=\frac{e E \tau}{m}
$$
where, $e=$ charge on electron,
$E=$ electric field,
$\tau=$ relaxation time
and $m=$ mass of the electron.
Since,
$$
\therefore \quad v_{d}=\frac{e V \tau}{m l}
$$
Since, $e, V, m$ and $l$ are constant .
$$
\therefore \quad v_{d} \propto \tau
$$
On increasing the temperature of metal wire, relaxation time decreases, therefore drift velocity of electrons also decreases.
But on increasing temperature of metal wire, thermal velocity of electron increases.
Looking for more such questions to practice?
Download the MARKS App - The ultimate prep app for IIT JEE & NEET with chapter-wise PYQs, revision notes, formula sheets, custom tests & much more.