Question

A u-shaped bar is resting in two cups of mercury through which a current can pass. It is oriented at right angles o a uniform magnetic of o.S T. Our goal here is to find the current required and its direction, (left or right) in 2. order to lift the bar against its own weigh You will need to sketch the situation, include all directions of fields, forces the current required to lift the bar. Let the magnetic field be into the page. t. The bar has a mass of 120 grams and a length in the field of 15 em. and current direction and calculate

Answer 1

The magnitude of the magnetic force is FB- F,I =匠ㄨ , where I is Current flowing through the bar, L is a vector of length equal to that of the bar L = 15 [cm] = 0.15 [m] oriented with the current (see Figure) and is Magnetic field with magnitude B = 0.5 [7] Since is oriented at right angles to the uniform magnetic field, then L is also perpendicular to B, and applying the definition of cross product, we get FILB Replacing in Newton's equation: 1LB-mg = 0 and from here I = mg Substituting numerical values in previous equation, we obtain: 1 LB 0.120 (9.81) 0.15(0.5) 1 = 15.696 [A] -