According to the figure, a uniform bar of length L carries a current I in the direction from point "a" to point "b". The bar is in a uniform magnetic field directed toward the page. Consider the torque about an axis perpendicular to the bar at point "a" that produces the force that the magnetic field exerts on the bar. Based on the above, answer the following question: What must be the current ? in the bar to be in rotational equilibrium when it is at an angle θ = 30° above the horizontal? If the bar has a mass of 0.0120 kg and is 30 cm long and rotates frictionless about an axis perpendicular to the bar at point "a" and is in a uniform magnetic field that is directed toward the page and has magnitude B = 0.150 T. (The gravitational force on the bar acts in the -y direction). Note: you must draw diagrams.

According to the figure, a uniform bar of length L carries a current I in the direction from point "a" to point "b". The bar is in a uniform magnetic field directed toward the page. Consider the torque about an axis perpendicular to the bar at point "a" that produces the force that the magnetic field exerts on the bar. Based on the above, answer the following question: What must be the current ? in the bar to be in rotational equilibrium when it is at an angle θ = 30° above the horizontal? If the bar has a mass of 0.0120 kg and is 30 cm long and rotates frictionless about an axis perpendicular to the bar at point "a" and is in a uniform magnetic field that is directed toward the page and has magnitude B = 0.150 T. (The gravitational force on the bar acts in the -y direction). Note: you must draw diagrams.