1. Physics E1-E6 tests are in your folders on front desk. Printouts of all grades and your midterm will be given next week 141 possible No. of students 90-1004 120-140280-901 110-119370-801 100-109460-702

2. Chapter E7 Magnetic Fields Problems due Wednesday E7B.1, E7B.2, E7B.7, E7B.8

3. Magnetic Fields  Every magnet has exactly two poles North and South North and South  Like poles repel, unlike poles attract  It is impossible to isolate a north pole from a south pole, they always exist in pairs.  Ferromagnetic materials are attracted to either pole  North poles point north So what magnetic pole is at the north pole of the Earth? So what magnetic pole is at the north pole of the Earth?

4. Magnet field  A region of space where a magnet feels a force.  A moving charge in a magnetic field feels a force given by the equation: This is the easiest way to know there is a magnetic field Forcecharge velocity Magnetic field

5. Units 1 gauss≡10 -4 Tesla Magnetic field of Earth = ~.5 gauss Everything on this page should be on your formula sheet!

6. Magnetic force on a current  A wire with a current has moving charges so the wire feels a magnetic force.  This is what makes electric motors work. Magnetic force on the wire Length of the wire Current in the wire Magnetic field

7. What is the direction of the force? Magnetic Field

8. What is the direction of the force on each section of the coil below? Magnetic field is into the screen. I current

9. What is the direction of the force on a positive particle moving as shown? Magnetic field is into the screen. current A charged particle can be contained in a ring by a magnetic field.

10. When a charged particle enters a magnetic field at the correct angle its path is a helix.

11. IB and B  IB is the magnetic field in relativistic units.  B is the magnetic field in mks units.  We will usually use B instead of IB.

12. What is the direction of the force on each section of the coil below? I current

13. The electric motor is turned by a magnetic force. The current changes as the armature reaches a magnet, making it repel and keep turning. Electric Motor

14.  Problems due Wednesday  E7B.1, E7B.2, E7B.7, E7B.8