The Universe of Waves
A wave is a disturbance that transfers energy through a medium or through space.
Mechanical vs. Electromagnetic Waves
Mechanical Waves: Require a medium (a substance) to travel through. The wave is a propagation of a disturbance within the medium.
Examples: Sound waves (travel through air, water, solids), ocean waves, waves on a guitar string.
They cannot travel through a vacuum.
Electromagnetic (EM) Waves: Do not require a medium. They can travel through the vacuum of space. They are disturbances in electric and magnetic fields.
Examples: Light, radio waves, X-rays, microwaves.
All EM waves travel at the same speed in a vacuum: the speed of light (c), which is approximately 3 x 10⁸ m/s.
The Electromagnetic Spectrum
The EM spectrum is the entire range of EM waves, organized by frequency, wavelength, or energy.
Key Relationships:
Frequency (f) and Wavelength (λ): Inversely proportional. High frequency means short wavelength. (c = fλ).
Energy (E) and Frequency (f): Directly proportional. High frequency means high energy. (E = hf, where h is Planck's constant).
This means Energy is inversely proportional to Wavelength.
Order of Increasing Energy (and Frequency):
1.Radio Waves (Lowest energy, longest wavelength)
2.Microwaves
3.Infrared
4.Visible Light (ROY G BIV)
5.Ultraviolet
6.X-rays
7.Gamma Rays (Highest energy, shortest wavelength)
Visible light is just the tiny portion of this vast spectrum that our eyes have evolved to detect.