A metal rod of mass m and length l slides on two parallell frictionless rails.
A uniform magnetic field is directed perpendicular to the plane of the rails.
There is no external agent applying a force to the rod.
Show that v(t) = v0e^t/T
where T = mR/(Bl)²
The Attempt at a Solution
I don't know where to start. Shall I construct a differentialequation including dt and dA? If not the solution I would be greatful for some hints.