Spring in a magnetic field

1. Feb 16, 2014

Bananas40

1. The problem statement, all variables and given/known data

A mass is attached to a spring through which circulates an electric current. Will the mass move?

2. Relevant equations

F = I l $\times$ B ?

3. The attempt at a solution

A spring is geometrically equivalent to a solenoid. Therefore, the current would generate a magnetic field which goes through the spring. What I'm not sure of is whether this magnetic field exerts a force on the solenoid or not.

Thank you.

2. Feb 16, 2014

BvU

Consider what F = I l × B of a small section of the spring does on the current in the next loop of the coil. What is the direction of the resulting force ? (Ideal) springs are supposed to extend/contract in repsonse to forces in which direction ?

Problem formulation is somewhat vague: was the current there when we opened our eyes, or was it switched on at that moment ?