Understanding Light

• Electromagnetic Spectrum: Visible light is just a small part of a broader spectrum that includes radio waves, microwaves, infrared, ultraviolet, X-rays, and gamma rays. All these forms of energy travel in waves, differing in wavelength and frequency.
• Wavelength and Color: The wavelength of light determines its color. Red has the longest wavelength, while violet has the shortest.

The Role of Water Droplets

• Spherical Prisms: Raindrops are essentially tiny spherical prisms. As light enters a raindrop, it slows down due to the denser medium (water). This change in speed causes the light to bend or refract.
• Dispersion: Different colors of light have different wavelengths and bend at slightly different angles. This separation of colors is called dispersion.
• Internal Reflection: Inside the raindrop, the light reflects off the back inner surface before exiting.
• Second Refraction: As the light exits the raindrop, it refracts again, further separating the colors.

The Rainbow's Arc

• Observer's Position: The angle between the incoming sunlight, the raindrop, and the observer's eye is crucial for seeing a rainbow. This angle is approximately 42 degrees.
• Full Circle: Rainbows are actually full circles, but we typically see an arc because the ground obstructs the lower half.

Additional Factors

• Rainbow Types: There are primary and secondary rainbows. Secondary rainbows are fainter and have reversed color order due to an extra internal reflection.
• Double Rainbows: Occasionally, two rainbows can be seen due to multiple internal reflections.
• Rainbow Intensity: The intensity of a rainbow depends on the size and distribution of water droplets, as well as the sunlight's angle.