* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Lecture 1: Introduction to Electromagnetism
Magnetic field wikipedia , lookup
Scanning SQUID microscope wikipedia , lookup
Electric machine wikipedia , lookup
Electric charge wikipedia , lookup
Superconducting magnet wikipedia , lookup
Hall effect wikipedia , lookup
Superconductivity wikipedia , lookup
Magnetoreception wikipedia , lookup
Magnetochemistry wikipedia , lookup
Electromotive force wikipedia , lookup
Electromagnetic radiation wikipedia , lookup
History of electrochemistry wikipedia , lookup
Magnetohydrodynamics wikipedia , lookup
Force between magnets wikipedia , lookup
Magnetic monopole wikipedia , lookup
Multiferroics wikipedia , lookup
History of electromagnetic theory wikipedia , lookup
Faraday paradox wikipedia , lookup
Eddy current wikipedia , lookup
Computational electromagnetics wikipedia , lookup
Electricity wikipedia , lookup
Electrostatics wikipedia , lookup
Maxwell's equations wikipedia , lookup
Mathematical descriptions of the electromagnetic field wikipedia , lookup
Lorentz force wikipedia , lookup
Welcome to electromagnetism • Welcome to electromagnetism! • I am Chris Blake and will be your lecturer for this section of the Physics 2A course • My contact details are [email protected], 9214 8624. You are welcome to contact me whenever you like! Lecture 1 : Welcome to Electromag • Importance of electromagnetism • Meaning of forces • Synthesis of ideas • Maxwell’s Equations • Summary of the course Importance of electromagnetism • Electromagnetism is everywhere in our lives Importance of electromagnetism • Electromagnetism is one of the fundamental forces that govern the physical Universe Importance of electromagnetism • How strong are electromagnetic forces? 𝑚1 𝑚2 𝐹𝑔 = 𝐺 𝑟2 𝑞1 𝑞2 𝑚1 𝑚2 𝐺 = 7 × 10−11 𝑁 𝑘𝑔−2 𝑚2 𝑞1 𝑞2 𝐹𝑒 = 𝑘𝑒 2 𝑟 𝑘𝑒 = 9 × 109 𝑁 𝐶 −2 𝑚2 • What is the ratio between the gravitational force 𝐹𝑔 and the electrostatic force 𝐹𝑒 between two isolated electrons (mass 9 × 10−31 𝑘𝑔, charge 1.6 × 10−19 𝐶) ? • Does your answer depend on the distance between the electrons? Importance of electromagnetism • Electrostatic forces are reduced in practice because matter is approximately electrically neutral Importance of electromagnetism • Electromagnetism is by far the strongest force in our everyday experience Importance of electromagnetism • Electromagnetism is by far the strongest force in our everyday experience Importance of electromagnetism • Other forces dominate on different scales … Meaning of forces • Coulomb’s Law tells us that like charges repel and unlike charges attract. But what causes one charge to feel the effect of the other? • How is a force transmitted across space? • Is a force transmitted instantaneously and, if so, does that violate special relativity? Meaning of forces • In our course, we consider that a force is transmitted through the electromagnetic field • An electric charge sets up an electric field in the region of space surrounding it • Other charges, placed in an electric field, will feel an electrostatic force Meaning of forces • In our course, we consider that a force is transmitted through the electromagnetic field • An electric current (or magnet) sets up a magnetic field in the region of space surrounding it • Other currents (or magnets), placed in a magnetic field, will feel a magnetic force Meaning of forces • More advanced physics courses will continue to refine this concept! Synthesis of ideas • Physics is about the synthesis of ideas : understanding apparently different phenomena as the joint consequences of a deeper reality • For example, in 1666 Newton realized that the same gravitational force causes both apples to fall downwards from trees on the Earth, and the Earth to orbit the Sun Synthesis of ideas • Electromagnetism represents another great synthesis of ideas. Prior to 1830, electricity and magnetism were considered separate phenomena Electricity Magnetism Synthesis of ideas • However, Faraday’s experiments demonstrated that a magnet, as well as a battery, can drive a current Electromagnetism Synthesis of ideas • Electricity and magnetism are therefore connected by deeper principles, which we will discuss Synthesis of ideas • Charges produce electric fields, and currents produce magnetic fields. But seen in a moving reference frame, a charge becomes a current! • Special relativity – which describes how physics is viewed in different reference frames – must allow us to transform electrostatics into magnetism Synthesis of ideas • The other great synthesis of ideas is that electromagnetism can explain optics (light waves) Synthesis of ideas • In this course will see that light waves are just vibrating electric and magnetic fields Maxwell’s Equations • Electromagnetism is governed by four simple and elegant equations : Maxwell’s equations • These equations are written in the mathematical language of vector calculus, which we will develop • In the following lectures we will introduce these equations, and the phenomena they represent, piece-by-piece Summary of the course • How an electric field is produced by charges (Lectures 2-5) • How a magnetic field is produced by currents (Lectures 7-9) • How these fields are modified in materials (Lectures 6, 11) • Electromagnetic forces and their applications (Lecture 10) • How a changing magnetic field produces an electric field, and a changing electric field produces a magnetic field (Lectures 12-13) • How these phenomena produce light (Lecture 14) Summary of the course • The electromagnetism course consists of … • 3 lectures a week (Monday 8.30am in BA802, Wednesday 10.30am in AGSE211, Thursday 2.30pm in BA802) • 1 tutorial a week (Thursday 12.30pm or 1.30pm) • 2 labs (Wednesday 4.30pm, Weeks 8/10 or 9/11) • 1 assignment (handed in Week 13) • Half the Physics 2A examination! Summary of the course • I look forward to working with you! • Just a reminder that my contact details are Chris Blake, [email protected], 9214 8624