6.2.1 Electromagnetic (EM) Waves

• What are electromagnetic waves?

  Transverse waves consisting of oscillating electric and magnetic fields at right angles to each other and the direction of wave propagation.
• At what speed do electromagnetic waves travel in a vacuum?

  Approximately $3 \times 10^8$ meters per second (m/s).
• How does the speed of electromagnetic waves change when passing through different mediums?

  The speed can decrease when they pass through different mediums like glass or water.
• What is the electromagnetic spectrum?

  The range of all types of electromagnetic radiation divided into different categories based on wavelength and frequency.
• What is the order of the electromagnetic spectrum from longest wavelength to shortest?

  • Radio Waves
  • Microwaves
  • Infrared (IR) Radiation
  • Visible Light
  • Ultraviolet (UV) Light
  • X-rays
  • Gamma Rays
• What mnemonic can help remember the order of the electromagnetic spectrum?

  "Raging Martians Invaded Venus Using X-ray Guns."
• What is wavelength (λ) in the context of electromagnetic waves?

  The distance between consecutive crests or troughs in a wave.
• How does wavelength change across the electromagnetic spectrum?

  It decreases from radio waves to gamma rays.
• What is frequency (f) in the context of electromagnetic waves?

  The number of wave cycles passing a point per second.
• How does frequency change across the electromagnetic spectrum?

  It increases from radio waves to gamma rays.
• How does the energy of electromagnetic waves relate to frequency?

  The energy increases with frequency; gamma rays are the most energetic, while radio waves are the least energetic.
• What is the wave equation for electromagnetic waves?

  The wave equation relates the speed of light (c), frequency (f), and wavelength (λ) as $c =$$f \times \lambda$.
• What is the value of the speed of light (c) in a vacuum?

  $3 \times 10^8 \, \text{m/s}$.
• What are practical uses of electromagnetic waves in daily life?

  • Communications: Radio and microwaves for broadcasting and mobile phones.
  • Medical Imaging: X-rays and gamma rays for diagnostics.
  • Remote Controls: Infrared waves for devices.
  • UV Light: Detecting counterfeit money, disinfecting water.
• What is the significance of understanding electromagnetic waves and their properties?

  It helps explain how different types of EM waves are used in technology and their potential risks.
• What is the wave equation used for in the context of electromagnetic waves?

  It is crucial for solving problems related to wave speed, frequency, and wavelength.