Two metal strips of negligible resistance are clamped parallel to each other on a horizontal floor with a separation  $l$  between them. A wire of mass m lies on them perpendicularly as shown in figure. A vertically downward magnetic field of strength B exists in the space.
One end of the strips is connected to a switch (K) and a capacitor of capacitance C charged to voltage $V_0.$ At t = 0 the key is closed. Neglect friction and self-inductance of the loop. 

The maximum possible value of the ratio of the maximum kinetic energy attained by  the rod to the energy initially stored in the capacitor (by appropriately choosing B) is  ___