A uniform metallic wire carries a current 2 ,A. when 3.4 ,V batte… - Vidyadip

MCQ

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 $l=............\,m$

A
$6.8$
✓
$10$
C
$5$
D
$100$

✓

Answer

Correct option: B.

$10$

b
$I =2\,A$

$\Delta V =3.4\,V$

Using Ohm's Law

$R =\frac{3.4}{2}=1.7 \Omega$

$1.7=\frac{\rho L }{ A }$

$L =\frac{1.7( A )}{\rho}$

$M =(\text { density volume })$

$Volume =\frac{8.92 \times 10^{-3}}{8.92 \times 10^3}=10^{-6}$

$L ^2=\frac{1.7}{\rho}\left(10^{-6}\right)=\frac{1.7}{1.7} \times 10^2$

$L =10\,m$

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