Lecture on Light and Color

Introduction

• Impact of COVID-19: Widespread chaos and disruption globally
• Optimism: Importance of a positive outlook and enjoying life despite challenges

Pre-test Questions

1. Highest Energy in Rainbow: D. Violet
2. Least Energy in Rainbow: B. Red
3. Property of Light for Rainbow Formation: B. Dispersion, Reflection, Refraction
4. Color that Bends the Most: D. Violet
5. Color with Shortest Wavelength: D. Violet

Color and Light

• Colors in the Electromagnetic Spectrum: Part of the visible spectrum
• Color Formation: Objects absorb or reflect wavelengths of light
• Wavelengths: Red has the longest, Violet has the shortest

Dispersion and Refraction

• Science of Rainbows: Due to the refraction and dispersion of light
• Refraction: Bending of light when it passes from one medium to another
• Reflection and Refraction: Key phenomena involved in producing visible colors

Experiment

• Materials Needed: Flashlight, big bowl, water, small mirror, paper
• Steps: Fill bowl with water, submerge part of mirror, use flashlight, observe colors on paper
• Result: Reflection of light and appearance of color bands (red, orange, yellow, green, blue, indigo, violet)

Key Concepts

• Light as Energy: Travels in waves
• White Light Composition: Mixture of many colors
• Arrangement of Colors: Determined by dispersion (ROYGBIV)
• Prism and Dispersion: Transparent materials like glass break white light into colors

Energy and Wavelength

• Color Energy Hierarchy:
  • Violet: Highest frequency (675-789 THz), shortest wavelength (380-445 nm)
  • Red: Lowest frequency (400-484 THz), longest wavelength (620-750 nm)
• Frequency and Energy: Higher frequency means more energy

Refraction in Daily Life

• Underwater Objects: Appear different due to refraction
• Coin in Water: Appears larger due to bending of light
• Optical Density: Measurement of a material’s ability to slow down light

Refraction Details

• Index of Refraction: Compares speed of light in a material vs. a vacuum
• Medium Changes: Light bends towards the normal line when entering a denser medium, away when entering a less dense medium
• Prism Example: Light bends differently based on color, with violet bending the most and red the least

Review Questions

1. Least Energy in Rainbow: C. Red
2. Violet Bent Most Because: D. Shortest wavelength
3. Separating Light: D. Prism
4. Splitting White Light: A. Dispersion
5. Refractive Index: C. Speed of light in a medium

Conclusion

• Reflection: Importance of understanding light and color in our world
• Encouragement: Continuation of learning and exploring