Question 41: Current Electricity

Question

Two identical conductors of lengths 1 and 31 respectively are maintained at the same temperature. They are given potential differences in the ratio $1: 3$. The ratio of their drift velocities is

Accepted Answer

Let the two rods have lengths $l_1=1$ and $l_2=3$, and the applied voltages be in the ratio
$ V_1:V_2=1:3. $
Since theyÃ¢ÂÂre made of the same material and have the same crossÃ¢ÂÂsection, their resistances go as
$      R\propto l      \quad\Longrightarrow\quad      R_1:R_2 = 1:3.    $
OhmÃ¢ÂÂs law gives
$      I_1 = \frac{V_1}{R_1},\quad      I_2 = \frac{V_2}{R_2}      \;\;\Longrightarrow\;\;      I_1:I_2      = \frac{V_1/R_1}{V_2/R_2}      = \frac{(1/1)}{(3/3)}      = 1:1.    $
The drift speed $v_d$ is proportional to the current (same carrier density and area), so
$      v_{d1}:v_{d2}=I_1:I_2=1:1.    $
Answer: Option C, $1:1$.

Answer

$1: 9$

Answer

$9: 1$

Answer

$1: 1$

Answer

$1: 3$

Current Electricity

Two identical conductors of lengths 1 and 31 respectively are maintained at the same temperature. They are given potential differences in the ratio 1: 3. The ratio of their drift velocities is

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