Not sure what else I could have done to prepare for the test. I did fine on the problems...it was the multiple choice that got me. I missed 10 and they were 2 points a piece. Personally I think the teacher is just too smart and can't simplify it for our level. But now I know what to expect on the tests and he drops the lowest test grade, so hopefully this will be the one that is dropped. But homework, labs, and quizzes are 45% of the final grade and I am making A's on all of those, so I'll be fine. Maybe we can get him to make a study guide for the multiple choice info.

Sorry it took so long to get these to you, and of course I need them to turn in Monday, so if you can't do them all by Monday, let me know. Thanks!

1. In a 1.25 T magnetic field directed vertically upward, a particle having a charge of magnitude 8.50 muC and initually moving northward at 4.75 km/s is deflected toward the east. A) what is the sign of the charge of this particle? Make a sketch to illustrate how you found your answer. B) Find the magnetic force on the particle.

5. At a given instant, a particle with a mass of 5.00 x 10^-3 kg and a charge of 3.50 x 10^-8 C has a velocity with a magnitude of 2.00 x 10^5 m/s in the +y direction. it is moving in a uniform magnetic field that has a magnitude 0.8 T and is in the -x direction. What are a) the magnitude and direction of the magnetic force on the particle and b) it's resulting acceleration?

8. A particle with a charge of -2.50 x 10^-8 C is moving with an instantaneous velocity of magnitude 40.0 km/s in the xy plane at an angle of 50 degrees counterclockwise from the +x axis. What are the magnitude and direction of the force exerted on this particle by a magnetic field with magnitude 2.00 T in the a) -x direction, and b) +z direction?

14. An alpha particle (a He nucleus, containing two protons and two neutrons and having a mass of 6.64 x 10^-27 kg) traveling horizontally at 35.6 km/s enters a uniform, vertical, 1.10 T magnetic field. a) What is the diameter of the path followed by this alpha particle? b) What effect does the magnetic field have on the speed of the particle? c)What are the magnitude and direction of the acceleration of the alpha particle while it is in the magnetic field? d) explain why the speed of the particle does not change even though an unbalanced external force acts on it.

23. singly ionized (one electron removed) atoms are accelerated and then passed through a velocity selector consisting of perpendicular electric and magnetic fields. The electric field is 155 V/m and the magnetic field is 0.0315T. The ions next enter a uniform magnetic field of magnitude 0.0175 T tthat is oriented perpendicular to their velocity. a) How fast are the ions moving when they emerge form the velocity selector? b) If the radius of the path of the ions in the second magnetic field is 17.5 cm, what is their mass?

28. A horizontal rod 0.200 m long carries a current through a uniform horizontal magnetic field of magnitude 0.067T that points perpendicular to the rod. If the magnetic force on this rod is measured to be 0.13 N, what is the current flowing through the rod?

33. A long wire carrying 4.50 A of current makes two 90 degree bends, as shown in figure 20.64. The bent part of the wire passes through a uniform 0.240 T magnetic field directed as shown in the fugure and confined to a limited region of space. Find the magnitude and direction of the force that the magnetic field exerts on the wire.

34. The 20.0 cm by 35.0 cm rectangular circuit show in figure 20.65 is hinged along side ab. It carries a clockwise 5.00 A current and is located in a iniform 1.20 T magnetic field oriented perpendicular to two of its sides, as shown. a) make a clear diagram showing the direction of force taht the magnetic field exerts on each segment of the circuit (ab, bc, etc.) b) Of the four forces you drew in part a, decide which ones exert torque about the hinge ab. Then calculate only those forces that exert this torque. c) Use your results from part b) to calculate the torque that the magnetic field exerts on the circuit about the hinge axis ab.

49. A long, straight telephone cable contains six wires, each carrying a current of 0.300 A. The distances between the wires can be neglected. A) if the currents in all six wires are in the same direction, what is the magnitude of the magnetic field 2.50 m from the cable? b) If four of the wires carry currents in one direction and the other two carry currents in the opposite direction, what is the magnitude of the field 2.50 m from the cable?

55. (Hint: wire= 4mm separation) A 2.0 m ordinary lamp extension cord carries a 5.0 A current. Such a cord typically consists of two parallel wires carrying equal currents in opposite directions. Find the magnitude and direction (attractive or repulsive) that the two segments of this cord exert on each other. ( You will need to inspect a lamp cord at home and measure or reasonably estimate the quantities needed to do this calculation.)

73. Three long, straight electric cables, running north and south, are tightly enclosed in an insulating sheath. One of the cables carries a 23.0 A current southward; the other two carry currents 17.5 A and 11.3 A northward. Use Ampere's law to calculate the magnitude of the magnetic field at a distance of 10.0 m from the cables.

75. Platinum is a paramagnetic metal having a relative permeability of 1.00026. A) What is the magnetic permeability of platinum? B) If a thin rod of patinum is placed in an external magnetic field of 1.3500 T, with its axis parallel to that field what will be the magnetic field inside the rod?