Understanding Waves and Light: Physics Fundamentals

Understanding Waves and Energy Transfer

A wave is a disturbance that travels a distance, carrying the energy which generated it. When the wave travels through a medium, like water or air, it does not displace the particles of the medium.

Characteristics of a Wave

• Wavelength: This is defined as the distance between two adjacent peaks or troughs of the wave. It is expressed in metres (m).
• Frequency: This is the number of oscillations or complete movements that a wave produces in one second. Its unit in SI is the Hertz (Hz).
• Speed of Propagation: This is the distance, e, that the wave travels divided by the time taken, t. It is expressed in m/s.

  Waves travel at a constant speed. Therefore:

  V_wave = e/t

  Which implies:

  e = V_wave · t

• Amplitude: This is the maximum height of a peak of a wave.

Types of Waves

Waves can be classified into two main groups:

• Mechanical Waves: They carry mechanical energy and require a material medium to propagate (e.g., sound).
• Electromagnetic Waves: They do not require a material medium to propagate, and they carry electromagnetic energy (e.g., light).

Light: An Electromagnetic Wave

Light is a type of electromagnetic wave. What we call visible light is made up of several lights or colors, ranging from red to violet. Every color has a different amount of energy, and this energy depends on the frequency.

Key Characteristics of Light

• It travels in a straight line.
• It travels at a constant speed. In a vacuum, light travels at 300,000 km/s, which is the highest speed we know; nothing can travel as fast as light.

How Matter Responds to Light

Depending on how different materials respond to light, they are classified as:

1. Transparent: They let light pass through, and we can see clearly through them.
2. Translucent: They let some light pass through, but we cannot see clearly through them.
3. Opaque: These objects do not let any light pass through them.

Light Pollution

Light pollution is the brightness of artificial light in the night sky. It is a consequence of the reflection of artificial light on air particles.

Fundamental Light Phenomena

Light interacts with surfaces and media in several fundamental ways:

Reflection

Reflection is the change in direction of light when it strikes an opaque surface and returns to its previous medium.

Refraction

Refraction is the bending of light when it crosses a surface that separates two different media. The light moves at a different speed in each medium.

Light Dispersion

Light dispersion is the scattering of light through media, like fog, which disperses light, separating it into its constituent colors.