A metallic rod of mass per unit length $0.5 \mathrm{~kg} \mathrm{~m}^{-1}$ is lying horizontally on a smooth inclined plane which makes an angle of $30^{\circ}$ with the horizontal. A magnetic field of strength $0.25 \mathrm{~T}$ is acting on it in the vertical direction. When a current $I$ is flowing through it, the rod is not allowed to slide down. The quantity of current required to keep the rod stationary is