Electromagnetic Waves and Matter: Reflection, Absorption, and Transmission

Understanding Light Interaction with Matter

• 💡 Light is understood as electromagnetic waves that propagate outwards from a source.
• 🎯 For simplicity, we can model the direction of light travel using rays, which are straight lines.

Reflection of Light

• 🪞 When light rays encounter a surface, they can bounce off, a phenomenon called reflection.
• 🧠 Our brains interpret reflected light as if it traveled in a straight line, which is why we see images in mirrors.
• 🍎 We see objects like apples because light from a source reflects off their surface into our eyes.

Absorption and Color

• 🌈 White light is a combination of all colors; objects appear a certain color because they absorb most colors and reflect one.
• 🔴 For example, a red apple reflects red light and absorbs other colors.
• ⚡ The energy of absorbed light is converted into thermal energy.

Transmission of Light

• 💧 Light can also pass through materials, known as transmission, as seen with glass and water.
• ✏️ When light transmits through different mediums, it bends, causing distortions like the apparent bending of a pencil in water.
• 🔭 This bending of light during transmission is the principle behind lenses used in telescopes and microscopes.
• 🌈 Different frequencies (colors) of light bend by different amounts, leading to phenomena like prisms separating white light into a spectrum and the formation of rainbows.

X-ray Imaging

• 🦴 While visible light is absorbed or reflected by skin, X-rays can transmit through soft tissues but are absorbed by bones.
• 📸 This differential absorption and transmission is why X-rays are used for imaging bones.

Key Principles

• 🔑 Whether light is reflected, absorbed, or transmitted depends on the frequency of the light and the properties of the material it encounters.