JEE PYQ: Current Electricity Question 49
Question 49 - 2019 (10 Apr 2019 Shift 1)
A current of 5 A passes through a copper conductor (resistivity = $1.7 \times 10^{-8},\Omega$m) of radius of cross-section 5 mm. Find the mobility of the charges if their drift velocity is $1.1 \times 10^{-3}$ m/s.
(1) $1.8,\text{m}^2/\text{Vs}$
(2) $1.5,\text{m}^2/\text{Vs}$
(3) $1.3,\text{m}^2/\text{Vs}$
(4) $1.0,\text{m}^2/\text{Vs}$
Show Answer
Answer: (4)
Solution
Mobility $\mu = \frac{v_d}{E}$, and $\rho = \frac{E}{J} = \frac{EA}{I}$, so $E = \frac{I\rho}{A}$. $\mu = \frac{v_d A}{I \rho} = \frac{1.1 \times 10^{-3} \times \pi \times (5 \times 10^{-3})^2}{5 \times 1.7 \times 10^{-8}} \approx 1.0,\text{m}^2/\text{Vs}$.
BETA
