Question

A uniform metallic wire carries a current $2 A$, when $34 V$ battery is connected across it The mass of uniform metallic wire is $892 \times 10^{-3} kg$, density is $892 \times 10^3 kg / m ^3$ and resistivity is $17 \times 10^{-8} \Omega- m$ The length of wire is :

• A. $l=10\, m$
• B. $l=100\, m$
• C. $l=5\, m$
• D. $l=6.8 \, m$

Answer 1

Answer: (A)

$l=10\, m$

Answer 2

I=2A
ΔV=3.4V
Using Ohm's Law R=23.4​=1.7Ω
1.7=AρL​
L=ρ1.7(A)​
M= ( density volume )
Volume =8.92×1038.92×10−3​=10−6
L2=ρ1.7​(10−6)=1.71.7​×102
L=10m