An insulated wire with a resistance of 184 m and a length of

An insulated wire with a resistance of 18.4 /m and a length of 23.5 m will be used to construct a resistor. First, the wire is bent in half, and then the doubled wire is wound on a cylindrical form (see figure) to create a 25.0 cm-long helix that has a diameter equal to 2.00 cm. Find the resistance and inductance of this wire-wound resistor.

Solution

Since the current in the two parts of the wire is in opposite directions. Consequently, the total flux in the coil is zero. So the inductance is zero.

L=0

Given

R/L =18.4 ohm/m

resistance of the wire is

R=18.4*23.5

R=432.4 ohms