# Magnetism (Current-Carrying Wires)

by Charanjit
Tags: currentcarrying, magnetism, wires
 P: 49 1. The problem statement, all variables and given/known data Two straight wires, each with a resistance of 0.170 ohm and a length of 3.90m, are lying parallel to each other on a smooth horizontal table. Their ends are connected by identical, non-conducting, light springs, each spring having an unstretched length of 1.08 cm. A wire of negligible resistance connects the wires at one end. When a switch is closed to connect a battery with a voltage of 49.0 V between the other ends of the wires, the wires move apart and come to rest with a separation of 1.57 cm Question: Find the force constants of the springs. 2. Relevant equations F=-kx (F/L)=(u0I1I2)/2Pi r 3. The attempt at a solution I tried to solve using the equations above for K, and does not work.
 P: 624 Did you modify the k in the spring equation to take into account the presence of both springs in a parallel arrangement?
 P: 49 Yes I did. This is what I got: F=-2kx (F/L)=(uI^2)/(2pi a) k=(uI^2L)/(4piax) I tried solving this, but got wrong answers. What I did: u=1.26e-6 (Constant given to use) I=144.1176 (Combining resistors in series and finding current) L=3.90 (Length of the wire) a=0.0157 (Seperation of the wires) x=0.0049 (stretch of the spring) Thats what I use, and I got 106 N/m. Can you verify that please?
 P: 7 Magnetism (Current-Carrying Wires) due to passing of current the magnetic field is created in the rods hence we know the formula F=vlb from that u can find the force and from F=kx u can find the spring constant
 P: 49 So what I have is correct? Can you check?
Mentor
P: 12,074
 Quote by Charanjit Yes I did. This is what I got: F=-2kx (F/L)=(uI^2)/(2pi a) k=(uI^2L)/(4piax) I tried solving this, but got wrong answers. What I did: u=1.26e-6 (Constant given to use) I=144.1176 (Combining resistors in series and finding current) L=3.90 (Length of the wire) a=0.0157 (Seperation of the wires) x=0.0049 (stretch of the spring) Thats what I use, and I got 106 N/m. Can you verify that please?
I agree, good job.

 Quote by dineshnaveen due to passing of current the magnetic field is created in the rods hence we know the formula F=vlb from that u can find the force and from F=kx u can find the spring constant