- Explain what is light and the properties of light waves Part 2 - Refraction Explain what happens when light moves through a transparent medium of different density

## Part 1: What is Light and its PropertiesLight is a form of **electromagnetic radiation**. This means it's a type of energy that travels as waves formed by oscillating electric and magnetic fields. These fields are perpendicular to each other and to the direction the light is traveling. Unlike sound waves, light waves don't need a medium to travel through; they can travel through the vacuum of space.**Properties of Light Waves:*** **Wavelength (λ):** The distance between two consecutive peaks (or troughs) of a wave. Wavelength determines the color of visible light. Shorter wavelengths correspond to bluer light, while longer wavelengths correspond to redder light.* **Frequency (f):** The number of wave cycles that pass a given point per second. Frequency is measured in Hertz (Hz).* **Speed (c):** The speed of light in a vacuum is approximately 3 x 10^8 meters per second. This is a constant, denoted by 'c'.* **Amplitude:** The height of the wave from its equilibrium position. Amplitude determines the intensity or brightness of the light.* **Polarization:** Light waves can oscillate in different directions. Polarization refers to the direction of the electric field's oscillation.* **Reflection:** When light encounters a surface, some of it bounces back. This is reflection.* **Refraction:** When light passes from one medium to another (e.g., air to water), its speed and direction change. This is refraction.* **Diffraction:** The bending of light waves as they pass through an opening or around an obstacle.* **Interference:** When two or more light waves overlap, they can either reinforce each other (constructive interference) or cancel each other out (destructive interference).## Part 2: RefractionRefraction occurs when light passes from one transparent medium to another with a different **optical density**. Optical density is a measure of how much a medium slows down the speed of light. A denser medium has a higher refractive index.When light moves from a less dense medium to a denser medium (e.g., air to glass):1. **Speed decreases:** Light slows down in the denser medium.2. **Direction changes:** The light ray bends *towards* the normal (an imaginary line perpendicular to the surface at the point of incidence).3. **Wavelength decreases:** While the frequency of the light remains constant, the wavelength decreases because the speed has decreased (speed = frequency x wavelength).When light moves from a denser medium to a less dense medium (e.g., glass to air):1. **Speed increases:** Light speeds up in the less dense medium.2. **Direction changes:** The light ray bends *away* from the normal.3. **Wavelength increases:** The wavelength increases as the speed increases, while the frequency remains constant.The amount of bending depends on the angle of incidence (the angle between the incoming light ray and the normal) and the refractive indices of the two media. Snell's Law describes the relationship between these factors:n₁sinθ₁ = n₂sinθ₂Where:* n₁ is the refractive index of the first medium* θ₁ is the angle of incidence* n₂ is the refractive index of the second medium* θ₂ is the angle of refractionIt's important to note that if the light enters the second medium perpendicular to the surface (angle of incidence = 0°), there's no change in direction, even though the speed and wavelength still change.