physics Problem?

Question

an unknown lenght of insulated copper wire is waved in the form of a coil. the wire has a circular cross-section of diameter d=1/16
if one connects it to a 2 v battery, current through the wire is 0.5 A .How long is the wire?

Answer 1

Use Ohm's law to figure the resistance .... Looks like about 4 ohms.

Calculate the cross section of the wire and look up the resistivity of copper. Given the cross section calculate the resistance per unit meter. R = resistivity x ( length / cross section) where length equals 1 . Given the resistance per meter, how many meters do you need to get 4 Ohms. It's that simple.