Question 38: Current Electricity

Question

Two wires A and B made of same material having length 10 cm and 40 cm respectively are connected in parallel to the same source of emf 10 V . What will be the ratio of the drift velocity of the electrons in the wire $A$ to the drift velocity in the wire $B$ ?

Accepted Answer

Since both wires have the same material and crossÃ¢ÂÂsection,
$$R\propto L\,, $$
so
$$R_A:R_B=10:40=1:4\,. $$
In parallel each wire has the same voltage $V$, so
$$I=\frac{V}{R}\quad\Longrightarrow\quad I_A:I_B=R_B:R_A=4:1\,. $$
The drift velocity
$$v_d=\frac{I}{nAe}$$
is proportional to the current $I$. Hence
$$v_{dA}:v_{dB}=I_A:I_B=4:1\,. $$
Answer (Option C):
$\displaystyle \frac{V_{dA}}{V_{dB}} = 4:1$.

Answer

$\frac{V_{d A}}{V_{d B}}=1: 4$

Answer

$\frac{V_{d A}}{V_{d B}}=1: 2$

Answer

$\frac{V_{d A}}{V_{d B}}=4: 1$

Answer

$\frac{V_{d A}}{V_{d B}}=2: 1$

Current Electricity

Two wires A and B made of same material having length 10 cm and 40 cm respectively are connected in parallel to the same source of emf 10 V . What will be the ratio of the drift velocity of the electrons in the wire A to the drift velocity in the wire B ?

Choose the correct answer: