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Unformatted text preview: Physics 21 Fall, 2009 Solution to HW-12 27-35 A long wire carrying 4.50 A of current makes two 90 bends, as shown in the figure. The bent part of the wire passes through a uniform 0.248 T magnetic field directed as shown in the figure and confined to a limited region of space. (a) Find the magnitude of the force that the magnetic field exerts on the wire. (b) Find the direction of the force that the magnetic field exerts on the wire. y z x is out of page Add the forces that act on each segment of the wire. Use the right hand rule to find the direction of the forces. The wire segments in the y direction have a total length of 60.0 cm, and forces on these two segments add up to the same as the total force on a single 60.0 cm (=0.6 m) segment. That force is F 1 = I l B = I (0 . 6 m) B ( k ) The force on the segment of wire in the z direction is F 2 = I l B = I (0 . 3 m) B ( j ) . The total force is the sum of F 1 and F 2 : F = IB (0 . 3 j . 6 k ) = (0 . 335 j . 670 k ) N . 27-39 A thin, 51.0 cm long metal bar with mass 770 g rests on, but is not attached to, two metallic supports in a uniform magnetic field with a magnitude of 0.470 T, as shown in the figure. A battery and a resistor of resistance 26.0 are connected in series to the supports. (a) What...
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