
Answer:
Explanation:
Current density J = i / A where i is current and A is cross sectional area
J = 5 / Ï x ( .1 x 10â»ÂČ )ÂČ
= 1.6 x 10â¶ A / mÂČ
b )
electric field applied E = V / l where V is potential difference and l is lemgth of rod
E = 75 / 1.5
= 50 v / m
c )
J = Ï E
J is current density , Ï is conductivity and E is electric field .
1.6 x 10â¶ = Ï Â x 50
Ï = 3.2 x 10⎠Ωâ»Âč mâ»Âč
Resistivity = 1 / Ï
= 1 / 3.2 x 10âŽ
= .3125 x 10â»âŽ
=3.125 x 10â»â”  Ω m