Electromagnetic Waves and the Electromagnetic Spectrum

Definition: Electromagnetic waves (EM waves) are waves that consist of electric and magnetic disturbances and do not require a medium to travel through; they can traverse empty space.
EM waves include visible light and many other types categorized by their frequencies.
Properties:
- Disturbance of the wave is always perpendicular to the direction of propagation.
- All EM waves travel at the speed of light, approximately 300,000 kilometers per second (or 186,000 miles per second).

Nature of Light: Light behaves as a wave. Unlike other types of waves (such as sound or water waves), it propagates without needing a physical medium.
Classification: EM waves are transverse waves.
Characteristics:
- Wavelength: The distance between consecutive peaks of a wave.
- Frequency: The number of waves that pass a point in a given time period.
- Amplitude: The height of the wave, which affects brightness.

Rays: When light travels, it does so in straight lines known as rays.
Interactions with Mediums: When a ray of light passes from one medium to another, several events can occur:
- Absorption: The medium absorbs the light and captures its energy, stopping the light.
- Reflection: Light bounces off the surface of the new medium (flat surfaces such as mirrors). The angle of incidence equals the angle of reflection.
- Refraction: Light bends when it moves into a new medium. An example is shining light through a prism, where different wavelengths are bent by different amounts.
Laser Light: A laser produces a sharp and narrow beam of light due to its coherence.

Reflection: Light reflecting off a flat, reflective surface appears to come from behind the surface.
Refraction: Occurs as light enters and exits a medium (such as glass). Shorter wavelengths of light refract more than longer wavelengths. When white light passes through a prism, it separates into its constituent colors (spectrum).

Definition: The electromagnetic spectrum encompasses all types of EM waves organized by their frequency, from low to high frequency.
- Visible Light: The range of light visible to the human eye, including colors from red (longest wavelength) to violet (shortest wavelength).
Wave Properties: As frequency increases, wavelength decreases. The spectrum can be segmented into different types of waves:
- Radio Waves: Longest wavelengths, used in telecommunications.
- Microwaves: Shorter than radio waves, used for communications and heating food.
- Infrared Waves: Invisible to the human eye; they can be felt as heat.
- Ultraviolet Light (UV): Beyond visible light; excessive exposure can cause skin damage.
- X-rays: Very short wavelengths; utilized in medical imaging.
- Gamma Rays: Shortest wavelengths and highest frequency; can impact cellular structures.