The magnetic pole near the Earth's north geographic pole is a south magnetic pole. scientists have not determined which one yet. north magnetic pole.

24. A beam of protons with a velocity of 4 x 105 ms-¹ enters a uniform magnetic field of 0.3 T at an angle of 60° to the magnetic field. The radius of helical path taken by proton beam is 25 (a) 0.036 m (c) 0.024 m A (b) 0.012 m (d) 0.048 m

You have discovered a new app on your cell phone that can measure the magnetic field. As you are playing with it, you discover that the magnetic field is significantly stronger than the earth's magnetic field in a particular location of the room. You wonder if it is due to magnetic field do to power lines running in your building. A blue print of the building shows that the nearest line is as shown below. Your sensor reads maximum magnetic field when you are located at point P. Calculate the magnetic field as a function of the current and the distances a and b. Segments BC and AD are arcs of concentric circles. Segments AB and DC are straight-line segments. a A b 120 D

You are assigned the job of building a very sensitive magnetic scale. Objects are hung from a horizontal rod through which an electric current is directed from left to right. The rod is loosely attached to a pair of vertical rails that allow it to slide up and down with almost no resistance. The entire scale is placed in an external magnetic field, and the current is adjusted until the rod and object levitate, balancing the downward gravitational force with an upward magnetic force. B? 1. In which direction must the external magnetic field point in order for your scale to work? 2. What current is needed to balance the scale if the combined mass of the rod and object is 1 kg, the length of the wire is 1 meter, and the magnitude of the external magnetic field is 0.1 Tesla?