A metal, u-shaped bar is situated so that its two ends are each resting in a cup of mercury. The bar is in a uniform magnetic field which is orthogonal to the bar. When a current is applied through the mercury and bar, it experiences a force that will send it flying upward.
(a) Draw a sketch and label all relevant vectors involved in this scenario.
(b) If the bar has mass of 200g, a length of 15 cm, and th magnetic field has a magnitude of 0.2T, what must be the minimum current(direction and magnitude) to lift the bar?