Lecture Notes: Electricity and Magnetism

Introduction

• Presenter: Dr. Hebert
• Core Concept: Electric and magnetic fields interact to produce forces.
• Topics to be covered:
  • Atom model (electron cloud, revised Bohr model)
  • Static electricity
  • Methods of charging
  • Conductors and insulators
  • Electric fields and magnetic fields
  • Electricity flow: current and voltage
  • Ohm's Law
  • Power, light bulbs, and circuits
  • Electromagnetic induction
  • Transformers
  • Types of circuits (series and parallel)

Basic Atomic Structure

• Nucleus contains protons (positive) and neutrons (neutral).
• Electrons orbit the nucleus and are negatively charged.
• Detailed study in chapters 8 and 9.

Static Electricity

• Examples: Shock from a doorknob, static cling from clothes, combing hair.
• Charging Methods:
  • Friction: Transfer of electrons through rubbing (e.g., hair and brush).
  • Conduction: Direct contact between materials.
  • Induction: Polarization process without direct contact.

Conductors and Insulators

• Conductors: Allow electrons to move freely (e.g., copper, gold, silver).
• Insulators: Prevent electron movement (e.g., rubber, plastic).
• Semiconductors: Intermediate conducting ability.

Electric and Magnetic Fields

• Electric Field Lines: Similar to magnetic field lines, strongest at poles.
• Magnetic Poles: North and South, repel like poles, attract opposite poles.
• Bar Magnet Demonstration: Visualize field lines with iron filings.

Electricity Flow: Current and Voltage

• Current (I): Flow of electricity, measured in amperes (amps).
• Voltage (V): Electric potential difference, measured in volts.
• Analogies: Water flow through pipes for understanding current and voltage.

Ohm's Law

• Formula: V = IR (Voltage = Current x Resistance)
• Resistance (R): Slows down current, measured in ohms (Ω).
• Examples: Calculated voltage and current using given resistance.

Power and Light Bulbs

• Power (Watts): Calculated as Voltage x Current.
• Energy Efficiency: LED bulbs vs. incandescent bulbs in energy use.

Electromagnetism

• Interaction: Electricity and magnetism interact in devices like motors and transformers.
• Magnetic Field from Current: Observed by Horstead; current produces a magnetic field.

Electromagnetic Induction

• Discovery by Faraday: Moving a magnet through a wire coil generates electricity.
• Applications: Generators in power plants, electromagnetic induction principles.

Transformers

• Function: Step up or step down voltage using coiled wires around an iron core.
• Importance: Adjust voltage levels for safe appliance operation.

Types of Circuits

• Series Circuits: Components in a single path; total voltage is the sum of all components.
• Parallel Circuits: Components in multiple paths; total voltage is the same, extends battery life.
• Applications: Household wiring, old and new Christmas lights.

Conclusion

• Advice: Review material, complete labs, and prepare for quizzes.
• Contact Information: Available for further assistance via call or text.