A thin strip `10cm` long is on a `U` shaped wire of negligible resistance and it is connected to a spring of spring constant `0.5Nm^(-1)` (see figure). The assembly is kept in a uniform magnetic field of `0.1T`, If the strip is pulled from its equilibrium position and released, the number of oscillations it performs before its amplitude decreaes by a factor of `e` is `N`. If the mass of the strip is `50` grams, its resistance `10Omega` air drag negligible, `N` will be close to:
