1. Electromagnetism University of British Columbia Physics 420 By: Jason Cheung

2. What is a Field? A region of space characterized by a physical property having a determinable value at every point in the region A region of space characterized by a physical property having a determinable value at every point in the region Examples: gravitational field, Electric field,and magnetic field Examples: gravitational field, Electric field,and magnetic field

3. Gravitational Field Defined as Defined as A = acceleration G = gravitational constant m = mass of big object r = distance to the center of the big object

5. Electric Field Electric field is defined as the electric force per unit Charge Electric field is defined as the electric force per unit Charge It is the surrounding charges that create an electric field It is the surrounding charges that create an electric field E = Electric Field F = Electric Force q = Charge E is measure in Force/Coulomb

7. Cathode Ray Tube Demo (CRT)

8. Magnetic Field Magnetic field is a field that exerts a force on a moving charge Magnetic field is a field that exerts a force on a moving charge A magnetic field can be caused either by another moving charge or by a changing of electric field or magnetic dipoles of materials A magnetic field can be caused either by another moving charge or by a changing of electric field or magnetic dipoles of materials

9. Magnetic Field is measure in Tesla Magnetic Field is measure in Tesla A simple formula to calculate Magnetic Field B = magnetic field F = Magnetic Force Q = charge V =velocity of the moving charge

10. Battery Demo

11. Charge moving in a magnetic field obeys the Right Hand Rule Charge moving in a magnetic field obeys the Right Hand Rule There are two types of RHR There are two types of RHR –Right Hand Rule #1 –Right Hand Rule #2

12. Right Hand Rule 1 The thumb represents the velocity of which the charge is going The thumb represents the velocity of which the charge is going The remaining fingers tell you the direction of the magnetic field The remaining fingers tell you the direction of the magnetic field example: example:

13. Right Hand Rule 2 I = direction of the charge I = direction of the charge B = direction of the Magnetic Field B = direction of the Magnetic Field F = Force act on the charge F = Force act on the charge –Palm Push Positive (*Remember!!)

15. Right Hand Rule Question

16. Magnetism example of pair and unpaired: N is unpaired, O is paired (one of them) What is magnetism? Magnetism is one of the phenomena by which materials exert an attractive or repulsive force on other materials. What causes magnetism in material? It is the unpaired electrons in the electron orbit cause magnetism

17. Remember SPDF?? (Chem 11) Electrons fall into electron shell according to Hund ’ s rule. Electrons fall into electron shell according to Hund ’ s rule. –Examples

18. Nitrogen -Electrons -Protons and Neutrons 1s22p3 Electron Configuration of Nitrogen Wrong 2s2 Right

19. There are four types of magnetism 1.Ferromagnetic2.Paramagnetic3.Diamagnetic 4.Ferrimagnetic(Not going to cover)

20. Material Susceptibility χm Vacuum0 Water -1.2*10 -5 Bi -16.6*10 -5 C -2.1*10 -5 O2 0.19*10 -5 Al 2.2*10 -5 Fe200 Co70 Ni110 Magnetism is Measure in Magnetic Susceptibility (χm) The more susceptibility of a material has, the more magnetic property it processes

21. Ferromagnetic Any material that possess magnetization WITHOUT an external magnetic field is ferromagnetic Any material that possess magnetization WITHOUT an external magnetic field is ferromagnetic large and positive susceptibility large and positive susceptibility Examples of ferromagnetic materials Examples of ferromagnetic materials Cobalt (Co) Susceptibility = 70 Iron (Fe) Susceptibility = 200

22. Iron electron configuration Fe: 1s2,2s2,2p6,3s2,3p6,4s2,3d6 Fe: [Ar],4s2,3d6 Ar: 1s2,2s2,2p6,3s2,3p6 = [Ar] “ Core ” [Ar] -The electrons seems to align spontaneously -Pure quantum mechanics effect

23. Why are some Ferromagnetic doesn ’ t attract one another? Has to do with the magnetic domain of the material Has to do with the magnetic domain of the material

24. Ferromagnetic material demo

25. Paramagnetic Any material that possess magnetization (i.e. attraction with other magnetized material) WITH an external magnetic field is paramagnetic Any material that possess magnetization (i.e. attraction with other magnetized material) WITH an external magnetic field is paramagnetic small and positive susceptibility small and positive susceptibility Examples of paramagnetic materials Examples of paramagnetic materials Aluminum Al 2.2*10-5 Susceptibility = 2.2*10-5 Platinum Pt

26. Aluminum electron configuration [Ne].3s2.3p1 Compare to Iron (Fe) [Ar] Fe: [Ar],4s2,3d6 the dipoles do not interact with one another and are randomly oriented in the absence of an external field due to thermal agitation, resulting in zero net magnetic moment What is the differences between the two?!

27. Paramagnetic and Ferromagnetic Demo (magnets and levitation)

28. Diamagnetic very weak and negative susceptibility to magnetic fields. very weak and negative susceptibility to magnetic fields. Negative susceptibility = repel against magnetic fields (diamagnetism) Negative susceptibility = repel against magnetic fields (diamagnetism) Positive susceptibility = attract to magnetic fields (para + ferromagnetism) Positive susceptibility = attract to magnetic fields (para + ferromagnetism)

29. Diamagnetism Examples of diamagnetic materials Examples of diamagnetic materials Gold Copper Human (mostly)

30. Diamagnetic Levitation Demo

31. Applications of Magnetism MRI (magnetic resonance images)Superconductors

32. Applications of Magnetism Maglev Trains Maglev Trains