Concise Summary of Electricity & Magnetism Concepts

  • Outline for Electricity & Magnetism

    • Week 4: Charge, Electrons & Protons, Coulomb’s Law

    • Week 5: Current, Voltage, Energy Transfer

    • Week 6: Ohm’s Law, Resistance, Resistivity

    • Week 7: Characteristic Curves, Ohmic & Non-Ohmic Devices

    • Week 8: Series & Parallel Circuits

    • Week 9: Electron Gun & Energy

    • Week 10: Magnetic Fields

    • Week 11: Magnetic Forces

    • Week 12: Assessment & Revision

  • Electricity Usage

    • Converts energy from various sources (wind, water, fossil fuels, nuclear) to power homes and workplaces.

    • Used in communication and medical imaging.

  • Basic Charges

    • Electron Charges:

    • Positively charged (Proton): qp=+1.6×10−19extCq_p = +1.6 × 10^{−19} ext{ C}

    • Negatively charged (Electron): qe=−1.6×10−19extCq_e = -1.6 × 10^{−19} ext{ C}

    • De Broglie Wavelength: λ=hmv\lambda = \frac{h}{mv}

    • h=6.63×10−34extJsh = 6.63 × 10^{−34} ext{ J s}

    • Electron mass: me=9.1×10−31extkgm_e = 9.1 × 10^{−31} ext{ kg}

    • Electron velocity: vv

    • Electrostatic Force using Coulomb’s Law: F<em>E=kq</em>0q1r2F<em>E = \frac{k q</em>0 q_1}{r^2}

    • k≈9×109extNm2extC−2k ≈ 9 × 10^9 ext{ N m}^2 ext{ C}^{-2}

  • Electrons & Protons

    • Electron Characteristics:

    • Mass: me=9.1×10−31extkgm_e = 9.1 × 10^{−31} ext{ kg}

    • Charge: −e=−1.6×10−19extC-e = -1.6 × 10^{−19} ext{ C}

    • Proton Characteristics:

    • Mass: mp=1.67×10−27extkgm_p = 1.67 × 10^{−27} ext{ kg}

    • Charge: +e=+1.6×10−19extC+e = +1.6 × 10^{−19} ext{ C}

  • Force Between Charges

    • Like charges repel, opposite charges attract.

    • Example of Electrostatic Force:

    • For charges of 2.0extμC2.0 ext{ μC} and 1.0extμC1.0 ext{ μC} at 0.30extm0.30 ext{ m}, FE=+0.20extNF_E = +0.20 ext{ N} indicates repulsion.

    • Increasing distance reduces the force by the square of the distance.

  • Wave-Particle Duality

    • Electrons behave as both particles and waves.

    • Wave-particle duality explores how observation affects electron behavior (Copenhagen interpretation).

  • Example Problems

    • Calculate the de Broglie wavelength of an electron: λ=1.46×10−7extm\lambda = 1.46 × 10^{−7} ext{ m}

    • Calculate the electrostatic force using Coulomb's law.

  • Reading Material

    • Gary’s notes, Advanced Physics for You: Chapters on Photons & Electrons, Electric Fields.