Electromagnetic Waves

Alexis Irlbeck

Main Points of Presentation

  • Define electromagnetic wave
  • Who discovered the electromagnetic wave
  • Properties of the wave
  • Interaction with matter
  • Relationship with particles
  • Types of EM Waves
  • Real uses of EM Waves

What is an Electromagnetic Wave?

An electromagnetic wave is a wave that is made from vibrating charges, is composed of changing electric and magnetic fields, and can travel through a vacuum.

Who Discovered Electromagnetic Waves?

James Clerk Maxwell - 1800s Scottish Physicist that is credited for theorizing electromagnetic radiation.


Heinrich Hertz - 1800s German Physicist that proved the theory of electromagnetic radiation by Maxwell.

How are Electromagnetic Waves Made?

  • Electric charge vibrates, and the surrounding electric field changes
  • Magnetic field surrounding electric charge changes
  • Vibrating electric charge is surrounded
  • Surrounded by a changing electric/magnetic field
  • Becomes a wave as the changing electric/magnetic fields continually create each other
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In Layman's Terms...

  • Electric Charge - Positive or negative
  • Electric Field - Area around said electric charge
  • Magnetic Field - Area around either a magnet or moving electric charge


Essentially, the positive or negative charge, or "thing," vibrates. The area around that charge begins to vibrate as well. Because the charge is in motion, it has a magnetic field, which changes while this is happening. The changing magnetic field creates a changing electric field, which creates a changing magnetic field, and so on. The point is that an electromagnetic wave is its own matter.

What Kind of Wave is This?

  • Vibrating electric and magnetic fields are perpendicular to each other
  • Travel outward from charge
  • Transverse
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Other Properties of an Electromagnetic Wave

Speed

  • Vacuum - All EM waves travel at 300,000 km/s, or "The Speed of Light"
  • Changes based on material it travels through
  • Slowest in liquids and fastest in gases


Wavelength and Frequency

  • Wavelength - measured same as any wave
  • Frequency of Wave = Frequency of vibrating charge that produces wave

Interaction With Matter

  • Can travel through matter, as well as space
  • When an object is encountered, the vibrating electric and magnetic fields exert forces
  • Forces are exerted on charged particles and magnetic materials that compose the object
  • Particles in object gain energy from this interaction
  • For ex., electromagnetic waves from sun make sidewalk hot

Relationship Between Electromagnetic Waves and Particles

  • Particle is a piece of matter
  • Electrons, or particles, create an interference pattern - It was originally thought only waves could do this
  • In this way, electrons behave like waves
  • Particles don't move as a wave
  • Photon is just a massless bundle of energy that acts as a particle
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Types of Electromagnetic Waves

The electromagnetic spectrum is the range of all frequencies of electromagnetic radiation. This is how electromagnetic waves are classified.
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Real-World Uses of Electromagnetic Waves

  • Radio - listen to radio
  • Microwave - Microwave mac & cheese
  • Infrared - TV remote control
  • Visible Light - You can't see without it
  • UV - Vitamin D (bone health)
  • X-Ray - x-ray broken bones
  • Gamma - Cancer treatment
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