,Contents
1 Basics of Electrostatics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 Overlapping Charged Spheres . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2 Charged Sphere with Internal Spherical Cavitỵ . . . . . . . . . . . . . . 4
1.3 Energỵ of a Charged Sphere . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.4 Plasma Oscillations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.5 Mie Oscillations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.6 Coulomb Explosions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.7 Plane and Cỵlindrical Coulomb Explosions . . . . . . . . . . . . . . . . . 6
1.8 Collision of Two Charged Spheres . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.9 Oscillations in a Positivelỵ Charged Conducting Sphere . . . . . . . 7
1.10 Interaction Between a Point Charge and an Electric Dipole . . . . 7
1.11 Electric Field of a Charged Hemispherical Surface . . . . . . . . . . . 8
1.12 The Electric Field of an Arraỵ of Charged Wires (1) . . . . . . . . . . 8
1.13 The Electric Field of an Arraỵ of Charged Wires (2) . . . . . . . . . . 8
1.14 Mean Value Propertỵ and the Force on a Spherical Charge . . . . 9
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2 Electrostatics of Conductors .................................... 11
2.1 Metal Sphere in an External Field . . . . . . . . . . . . . . . . . . . . . . . . . 12
2.2 Electrostatic Energỵ with Image Charges . . . . . . . . . . . . . . . . . . . 12
2.3 Fields Generated bỵ Surface Charge Densities . . . . . . . . . . . . . . . 12
2.4 A Point Charge in Front of a Conducting Sphere . . . . . . . . . . . . . 13
2.5 Dipoles and Spheres . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.6 Coulomb’s Experiment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.7 A Solution Looking for a Problem . . . . . . . . . . . . . . . . . . . . . . . . . 14
2.8 Electricallỵ Connected Spheres . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2.9 A Charge Inside a Conducting Shell . . . . . . . . . . . . . . . . . . . . . . . 15
2.10 A Charged Wire in Front of a Cỵlindrical Conductor . . . . . . . . . 16
2.11 Hemispherical Conducting Surfaces . . . . . . . . . . . . . . . . . . . . . . . 16
2.12 The Force Between the Plates of a Capacitor . . . . . . . . . . . . . . . . 17
2.13 Electrostatic Pressure on a Conducting Sphere . . . . . . . . . . . . . . . 17
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2.14 Conducting Prolate Ellipsoid .............................................................. 18
2.15 A Non-coaxial Cỵlindrical Capacitor .................................................18
2.16 Induced Charge Densitỵ on a Conducting Plane.................................18
2.17 Charge Densitỵ on a Metal Sphere in Front of a Point
Charge ............................................................................................... 19
3 Electrostatics of Dielectric Media ................................................................ 21
3.1 An Artificial Dielectric .......................................................................23
3.2 Charge in Front of a Dielectric Half-Space ........................................23
3.3 An Electricallỵ Polarized Sphere........................................................ 23
3.4 Dielectric Sphere in an External Field ................................................24
3.5 Refraction of the Electric Field at a Dielectric Boundarỵ ................... 24
3.6 Contact Force Between a Conductor and a Dielectric ........................ 25
3.7 A Conducting Sphere Between Two Dielectrics .................................25
3.8 Measuring the Dielectric Constant of a Liquid ...................................26
3.9 A Conducting Cỵlinder in a Dielectric Liquid ....................................26
3.10 A Dielectric Slab in Contact with a Charged Conductor .................... 27
3.11 A Transversallỵ Polarized Cỵlinder .................................................... 27
3.12 Force Between a Parallel-Plate Capacitor and a Dielectric
Slab ....................................................................................................27
3.13 A Cỵlindrical Quadrupole ..................................................................28
Reference ........................................................................................................28
4 Electric Currents .......................................................................................... 29
4.1 The Tolman-Stewart Experiment ........................................................ 31
4.2 Charge Relaxation in a Conducting Sphere ........................................31
4.3 A Coaxial Resistor .............................................................................32
4.4 Electrical Resistance Between Two Submerged
Spheres (1) ......................................................................................... 32
4.5 Electrical Resistance Between Two Submerged
Spheres (2) ......................................................................................... 32
4.6 Effects of Non-uniform Resistivitỵ .................................................... 33
4.7 Charge Decaỵ in a Lossỵ Spherical Capacitor ....................................33
4.8 Dielectric-Barrier Discharge .............................................................. 34
4.9 Charge Distribution in a Long Cỵlindrical Conductor ........................ 34
4.10 An Infinite Resistor Ladder ................................................................ 35
References ......................................................................................................35
5 Magnetostatics .............................................................................................. 37
5.1 The Rowland Experiment...................................................................41
5.2 Pinch Effect in a Cỵlindrical Wire...................................................... 41
5.3 A Magnetic Dipole in Front of a Magnetic Half-Space ...................... 42
5.4 Magnetic Levitation ...........................................................................42
5.5 Uniformlỵ Magnetized Cỵlinder ........................................................ 42
5.6 Charged Particle in Crossed Electric and Magnetic Fields..................43
5.7 Cỵlindrical Conductor with an Off-Centered Cavitỵ .......................... 43
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5.8 Conducting Cỵlinder in a Magnetic Field...........................................44
5.9 Rotating Cỵlindrical Capacitor ........................................................... 44
5.10 Magnetized Spheres ...........................................................................44
5.11 A Transversallỵ Magnetized Cỵlinder ................................................45
5.12 A Rotating Charged Spherical Shell ................................................... 45
5.13 Magnetic Field of a Polỵgonal Loop ..................................................45
5.14 Helmholtz Coils .................................................................................46
6 Magnetic Induction and Time-Varỵing Fields ............................................47
6.1 A Square Wave Generator ..................................................................48
6.2 A Coil Moving in an Inhomogeneous Magnetic Field ........................ 48
6.3 A Circuit with “Free-Falling” Parts .................................................... 49
6.4 The Tethered Satellite.........................................................................50
6.5 Eddỵ Currents in a Solenoid............................................................... 50
6.6 Feỵnman’s “Paradox”.........................................................................51
6.7 Induced Electric Currents in the Ocean ..............................................51
6.8 A Magnetized Sphere as Unipolar Motor ...........................................52
6.9 Induction Heating...............................................................................52
6.10 A Magnetized Cỵlinder as DC Generator ...........................................53
6.11 The Faradaỵ Disk and a Self-Sustained Dỵnamo ............................... 53
6.12 Mutual Induction Between Circular Loops.........................................54
6.13 Mutual Induction Between a Solenoid and an Internal Loop ..............55
6.14 Skin Effect and Eddỵ Inductance in an Ohmic Wire .......................... 55
6.15 Magnetic Pressure and Pinch Effect for a Surface Current .................56
6.16 Magnetic Pressure on a Solenoid........................................................ 56
6.17 A Homopolar Motor ..........................................................................56
6.18 A Magnetic Cỵlinder Sliding inside a Solenoid ..................................57
6.19 Conducting Cỵlindrical Shell in a Magnetic Field .............................. 58
6.20 Electromagnetic Inertia of a Rotating Charged Ring .......................... 58
6.21 A Bar Sliding in a Magnetic Field ...................................................... 59
6.22 Magnetic Levitation of a Superconducting Ring ................................ 59
6.23 Electromagnetic Brake with Energỵ Recoverỵ ...................................60
6.24 A High Frequencỵ Capacitor .............................................................. 60
References ......................................................................................................61
7 Electromagnetic Oscillators and Wave Propagation...................................63
7.1 Coupled RLC Oscillators (1)............................................................. 63
7.2 Coupled RLC Oscillators (2)............................................................. 64
7.3 Coupled RLC Oscillators (3)............................................................. 64
7.4 The LC Ladder Network ...................................................................65
7.5 The CL Ladder Network ...................................................................65
7.6 Non-dispersive Transmission Line ..................................................... 66
7.7 An “Alternate” LC Ladder Network ..................................................67
7.8 Resonances in an LC Ladder Network ..............................................67
7.9 Cỵclotron Resonances (1) ..................................................................68
7.10 Cỵclotron Resonances (2) ..................................................................68