Current Electricity Question 5
Question 5 - 25 January - Shift 1
A uniform metallic wire carries a current $2 A$. when $3.4 V$ battery is connected across it. The mass of uniform metallic wire is $8.92 \times 10^{-3} kg$. density is $8.92 \times 10^{3} kg / m^{3}$ and resistivity is $1.7 \times 10^{-8} \Omega-m$. The length of wire is :
(1) $l=6.8 m$
(2) $l=10 m$
(3) $l=5 m$
(4) $l=100 m$
Show Answer
Answer: (2)
Solution:
$I=2 A$
$\Delta V=3.4 V$
Using Ohm’s Law
$R=\frac{3.4}{2}=1.7 \Omega$
$1.7=\frac{\rho L}{A}$
$L=\frac{1.7(A)}{\rho}$
$M=($ density volume $)$
Volume $=\frac{8.92 \times 10^{-3}}{8.92 \times 10^{3}}=10^{-6}$
$L^{2}=\frac{1.7}{\rho}(10^{-6})=\frac{1.7}{1.7} \times 10^{2}$
$L=10 m$
