Week 23 (Jan. 27 - Jan. 31)
Reading: Magnetic fields (Chap. 29)
Key Topics: magnetic poles, earth's magnetic field, magnetic materials, ferromagnetism, paramagnetism, curie temperature,
Key Topics: magnetic poles, earth's magnetic field, magnetic materials, ferromagnetism, paramagnetism, curie temperature,
Lab: Magnetism laboratory
Week 23 homework Problems:
Week 23 homework Problems:
- Magnetized compass needle: Carefully sketch the orientation of a magnetized compass needle when placed at several locations in the vicinity of a spherical ``terrella" (a) which is unbroken, (b) which has been split in half along the equator and the two halves slightly separated, (c) which has been split in half along a line joining the poles. Be sure to label the magnetic north ends of the terrella and the compass needle so things are oriented correctly.
- Magnetic field lines: Sketch the magnetic field lines in the vicinity of (a) a bar magnet, (b) two bar magnets placed end-to-end, slightly separated, with the north of one facing the south of the other, (c) same as previous but with the north poles facing one another, (d) a circular loop of wire carrying an electrical current, (e) a long helical coil of wire carrying an electrical current.
- Electron near earth's equator: Consider an electron near earth's equator. In which direction will it be deflected if its velocity is directed (a) downward, (b) northward, (c) westward, (d) southeastward?
- Suspending a wire magnetically: A wire having a mass per unit length of 0.5 grams/cm carries a 2.0 ampere current horizontally to the south. What are the magnitude and direction of the minimum magnetic field needed to lift this wire vertically?
- Proton in a magnetic field: A proton is moving at 4000 km/sec through a magnetic field of 1.7 tesla. It experiences a force of 8.2e-13 Newtons. (a) What is the angle between the proton's velocity and the field? (b) Is it possible for the field to exert zero force on the moving proton? If so, how?
