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23. A conductor which is 30 cm long with a mass of 20 g is suspended horizontally in a magnetic field whose magnetic flux density is 0.12 T. What current is required in order that the magnetic force balances the gravitational force? (5.5 A) 24. If a 45 mg conductor that is 15 cm long is accelerating upward (against gravity) at 4.19 m/s in a 5.0 mT field, how much current must be flowing in the conductor? (0.84 A) 25. Trace out the path of the positive particle in the indicated B (into paper] magnetic field. B 26. Three particles move through a constant magnetic field and follow the paths shown in the drawing. Determine whether each particle is 12 positive, negative, or neutral. Give reasons for your answers. B (into paperi 27. Three particles have identical charges and masses. They enter a constant 3 magnetic field and follow the paths shown in the picture. Which particle is moving fastest, which is moving slowest? Justify your answer.28. A magnesium ion (Me?*) traveling at 60 000 m/s enters a mass spectrometer with a magnetic field of 0.0800 T at an angle of 90" to the field. What is the radius of the curve followed by the magnesium ion? (9.39 x 10 m) 29. The solar wind is a thin hot gas given off by the sun in all directions. Some of the charged particles enter the magnetic field of the Earth and can experience a magnetic force. Suppose some charged particles traveling at 9.0 x 10" m/s encounter the Earth's magnetic field at an angle of 90" where the magnitude of the field is 1.2 x 10"T. Find the radius of the circular path on which the particle would move it were (a) an electron and (b) a proton. (4.3 x 10* m, 7.8 x 105 m) 30. An alpha particle with a speed of 4.4 x 10" m/s moves perpendicular to a 0.75 T magnetic field in a circular path with a radius of 0.012 m. What is the magnitude of the charge on the helium nucleus? (3.2 x 10 19 () 31. An ion source in a particular mass spectrometer produces deuterons (a deuteron has twice the mass of a proton, but the same charge). Each deuteron is accelerated from rest through a potential difference of 2000 V after which it enters a 0.600 T magnetic field. Find the radius of the circular path. (0.0152 m) 32. A mass spectrometer uses a potential difference of 2.00 kV to accelerate a singly charged ion to the proper speed. A 0.400 T magnetic field bends the ion into a circular path of radius 0.226 m millimeter. What is the mass of the ion? (3.27 x 10 25 kg)Lesson 3: Induced Magnetic Fields 34. For each situation to the right, determine the polarity of the induced magnetic field and the direction of induced electron flow for each of the following cases. Indicate which end of bj [8] the "generator" wire becomes a N La negative terminal in each case. (A) N (A] 35. An aluminum airplane is flying west, parallel to the ground, at 350 m/s. The Earth's magnetic field produces a downward component of 8.0 x 10 T. For this question, treat the wing as a conducting rod. Which wing tip would be negatively charged, the wing on the north side or the south side of the plane? Support your answer with a diagram. (the north side)36. A positively charged sphere is suspended between two large metal plates as shown in the diagram. A wire is placed between the poles of a horseshoe magnet and connected to the metal plates. When the wire is drawn horizontally to the right the charged ball is observed to swing toward the right-hand metal plate. a) Determine the direction of the induced electron flow in the wire in the horseshoe magnet. Explain. b) Is the top pole of the magnet a north pole or a south pole? Explain. A wire Is pulled to the right. V Flat metal plates