Question

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3. The resistivity of gold is 2.44 x10^-8 ohm.m at room temperature. A gold wire that is 0.9 mm in diameter and 14 cm long carries a current of 940 mA. What is the electric field in the wire9 A) 0.036 V/m B) 0.0090 V/m C) 0.028 V/m D) 0.046 V/m E) 0.090 V/m

Answer 1

resistance=resistivity*length/area

area=pi*diamter^2/4

putting the values,

resistance=5.369 mili ohms

current is given as 940 mA

then voltage=current*resistance=5.047 mV

as we know electric field=voltage/distance

where distance=0.14 m, here

so answer=0.036 V/m

option A is correct.