Question

When 20 Vis applied across a wire that is 10m long and has a 0.30 mm radius, the current is 10 A. a) Find the resistivity of the wire. b) What material is the wire most likely made from

Answer 1

(a) If (L) is the length of a wire, A is the area of cross section and is the resistivity of the wire, then the resistance (R) of the wire is given by the equation,

If r is the radius of the wire, A = r2.

From the above equation we can write resistivity as,

Given the applied voltage (V) = 20V, lenhth of the wire (L) = 10m, its radius (r) = 0.30mm = 0.30 x 10-3m and the current (I) = 10A.

By Ohm's law

Substituting the values in the eqquation of resistivity, we get

(b) Tungsten has the resistivity of 5.60 x 10 -8m. So the wire is most likely made up of Tungsten.