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Question 1 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 that is directed into the page. Consider the torque about an axis perpendicular to the bar at point a that is due to the force that the magnetic field exerts on the bar. (a) Suppose that an infinitesimal section of the bar has length dx and is located a distance x from point a. Calculate the torque do about point a due to the magnetic force on this infinitesimal section. (b)Use t = sdt to calculate the total torque t on the bar. (c) Show that u is the same as though all of the magnetic force acted at the midpoint of the bar. x В x xbx 11 dx ax