Question

eg

An electric field of 16 V/m is produced through a cylindrical wire that has uniform radius of 1.8 mm. If the resistivity of the material is ρ= 6.8x10-6 Ω.m, calculate the current passing through the wire.

Select one:
a. 18 A
b. 32 A
c. 24 A
d. 12 A

Answer 1

Area of the wire, A = * R²
Where R is the radius of the wire.
A = * (1.8 * 10^-3)²
= 10.18 * 10^-6 m²
Consider the length of the wire as L
The resistance of the wire, R = ( * L) / A
Where is the resistivity of the wire,
R = [(6.8 * 10^-6) * L] / (10.18 * 10^-6)
= 0.668 * L
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The voltage drop in the wire, V = E * L
Where E is the electric field
V = 16 * L
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Current, I = V / R
= (16 * L) / (0.668 * L)
= 24 A (option c)