Question 276: Current Electricity

Question

(A) The drift velocity of electrons decreases with the increase in the temperature of conductor.
(B) The drift velocity is inversely proportional to the area of cross-section of given conductor.
(C) The drift velocity does not depend on the applied potential difference to the conductor.
(D) The drift velocity of electron is inversely proportional to the length of the conductor.
(E) The drift velocity increases with the increase in the temperature of conductor.
Choose the correct answer from the options given below :

Accepted Answer

We know, Resistivity $ho=\frac{m}{n e^2 	au}$
Where $	au$ is relaxation time As temperature $\uparrow, 	au \downarrow, ho \uparrow, \mathrm{R} \uparrow, \mathrm{i} \downarrow, \mathrm{v}_{\mathrm{d}} \downarrow$ as $i=$ ne $\mathrm{A} v_{\mathrm{d}}$
Statement (A) is correct and hence statement (E) is incorrect.
$$
\mathrm{R}=ho \frac{l}{A}, I=\frac{V}{R}=\frac{V A}{ho l}=n e A v_d ightarrow v_d=	ext { constant }
$$
For a given $\mathrm{V}, v_{\mathrm{d}}$ is independent of $\mathrm{A}$. Hence, statement (B) is incorrect
Form above $v_d \propto$ V statement (C) is also incorrect. Since $v_d \propto \frac{1}{\ell}$ as seen from above statement, so statement (D) is correct.

Answer

(A) and (B) only

Answer

(A) and (D) only

Answer

(B) and (E) only

Answer

(B) and (C) only

Current Electricity

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