Electromagnetic field, Week 4

We learn about magnetic induction and alternating currents. We cover Chapter 6-7 in book: "Magnetic Induction and Magnetic Energy", "Alternating currents and transients"

• Monday, Jan 8th, Peter will be teaching (I will teach rest of the week). Use this opportunity of having him around for asking questions. Is there something that is not clear. Would you like to hear explenation of something in Swedish?
• For Monday, try to refresh yourself on Lorentz force, Ampere's law etc.
• Do not forgett "extra points exam" on Wedensday 10:00-10:45. Open book exam 10% (it's worth preparing for it).
• IMPORTANT: During the last lecture, last 15 minutes, what I have said was not correct. We will sort it out on Wedensday after the exam. However, there are few things for you to think about before the exam:
• I have made mistake assuming that D (and correspondingly H field) were always the same irrespecitively whether dielectric (diamagnet) is present or not.Think why this is not true?
• More specifically, I have used the equation div D=rho_free (which is correct) to ``conclude'' that D always has to be the same with or without dielectric. What is wrong with this statement? Is differential equation sufficient? Is there something we have to suplement it with?
• During the problem solving class we have discussed that magnetic material placed in field B₀ gets magnetized itself and produces additional field B_M. We have make drawings of B=B₀+B_MThink how to use this example to prove that my statement that H is always same is completely wrong.
• Think about reasons why you have not complined during the lecture: perhaps you have not dared, was I too convincing/forceful etc. We'll have to talk about it.

08/1 2001 (Mon) 10.00-10.45 (Mikro) "Electromagnetic Induction and Magnetic Energy"

• 6.1 Induction  (in detail)
• 6.1.1 Motional electromotive force (in detail)

• 6.1.2 Faraday's and Lentz's laws (in detail),
• 6.1.3 Examples of induction (just few comments, you'll have to do the rest at home)
• 6.1.4 The differential form of Faraday's law (in detail)

10/1 2001 (Wed) 10.00-10.45 (FL11)  "Extra points exam"

• to remind you, "extra points" means that you can gain some presentage points but this is not compulsory
• it you solve all tasks you will get 10%
• open book exam (means you can have everything you want except mobile phone turned on)
• 4 questions in total, 2 from electrostatics and 2 from magnetostatics
• this time you'll have to do a bit of calcualtion (you will not need calculators)
• expect problems similar in spirit to the ones we have discussed during our last lecture (charge close to bucked of water, etc.)

• 6.2 Self inductance and mutual inductance (we will need it for circuits)
• 6.2.1 Self-inductance (we discuss it in detail)
• 6.2.2 Mutual inductance (not in detail, just that you know what the whole thing is about, you must have understanding of important concepts)
• 6.3 Energy and forces in magnetic fields
• 6.3.1 The magnetic energy stored in conductor (in detail)
• 6.3.4 Discussing meaning of eq. 6.3

11/1 2001 (Thu) 10.00-10.45 (Mikro) Maxwell's equations and waves

• continuity equation, displacement current. etc/
• from Maxwell's eq. to wave equation

• 7.1 Alternating current generators
• 7.2 Amplitude, phase and period
• 7.3 Resistnce, capacitance and inductance in A.C. circuits
• 7.4 The phasor diagram and complex impedance
• 7.5 Power in A.C. circuits (you'll have to do that at home)
• 7.6 Resonance (in detail, this is very important topic)
• 7.7 Transients (do it at home)

11/1 2001 (Thu) 13.15-14.00, 14.15-15.00 (FL10+FL12) Problem solving

• Problem 10.1 (you'll get some feeling displacement current)
• Some problem about electromagnetic waves. Possibly derivation the refraction law
• If there is time left we can discuss problems you might have had while working on your own.