Answer to Question #145493 in Electric Circuits for Edward Lawerence

Question

The aluminum wire has a cross-sectional area of 40 mm
2
. The voltage at its ends is 3 mV.
Какова длина провода, если по нему течет ток силы 0,5 А? What is the length of the wire if a current
of 0.5 A flows through it? The electrical resistivity of aluminum is 0,026 ·m.

Answer 1

The resistance of wire is

$R=\frac{U} {I} =\rho\frac{l} {S},$

where U - the voltage at the ends of wire,

I - the current through the wire,

$\rho$ - resistivity of aluminium,

$l$ - length of the wire,

S - cross-sectional area of the wire.

Length of the wire from equation above is

$l=\frac{US} {\rho I} = \frac {3\cdot 10^{-3}\cdot 40 \cdot 10^{-6} }{0.026\cdot 0.5}=9.23\cdot 10^{-6} \space m$

Answer: $9.23\cdot 10^{-6} \space m$