Electromagnetism Lecture Notes

Introduction to Electromagnetism

• Interaction between electric charges and magnetic fields.
• One of the four fundamental forces of nature.
• Word formed from "electricity" and "magnetism."

Electricity

• Example: Rubbing a balloon on hair.
  • Hair stands on end, balloon sticks to walls.
  • Demonstrates static electricity.
• Static Electricity
  • Rubbing transfers electrons from hair to balloon.
  • Balloon becomes negatively charged, hair positively charged.
• Electric Current
  • Defined as the flow of electrons through a material.

Magnetism

• Example: Bar magnet with iron filings.
  • Filings form patterns around the magnet.
  • Patterns represent magnetic fields.
• Magnetic Field
  • Region around magnetic material where it exerts magnetic force.

Connection Between Electricity and Magnetism

• Moving electric charge creates a magnetic field.
• Changing magnetic field creates an electric field.
• This interaction is known as electromagnetism.

Electromagnets

• Created by winding wire around an iron nail and connecting to a battery.
• Electric current creates a magnetic field, magnetizing the nail.
• Principle used in motors and generators.

Power Generation

• Power Plants
  • Use generators to convert mechanical energy to electrical energy.
  • Generators use magnets and coils of wire.
  • Turbines spin, moving magnets and generating electricity.

Electromagnetic Waves

• Enable use of mobile devices for videos.
• Created by interaction of electric and magnetic fields.
• Properties
  • Travel at the speed of light.
  • Oscillate perpendicular to each other and the wave's direction.
• Electromagnetic Spectrum
  • Includes radio waves, microwaves, infrared, UV, x-rays, gamma rays.
  • Visible light is part of this spectrum.

Practical Examples of Electromagnetism

• WiFi routers, phones, laptops, credit card strips, toaster coils, microwave ovens, bedroom lighting.
• Challenge: List 5 more daily life examples of electromagnetism.

Fun Fact

• Speed of light: Earn brownie points by providing its exact value!