🌈 Rainbow mind map: Electromagnetic Waves and Spectrum

Electromagnetic Waves and Spectrum

Composition of White Light

Composition of White Light

White light is composed of all the colors of the visible spectrum. When passed through a prism, it disperses into its constituent colors: red, orange, yellow, green, blue, indigo, and violet (ROYGBIV).

This phenomenon demonstrates that what we perceive as white light is actually a combination of different wavelengths, each corresponding to a specific color.

Newton's Early Experiments

Newton's Early Experiments

In the 1660s, Isaac Newton conducted groundbreaking experiments with prisms. He darkened his room and made a small hole in his window shutter to let in sunlight, which he then passed through a prism.

The prism refracted the light and projected a spectrum of colors onto the opposite wall, proving that white light was composed of multiple colors.

Prism Experiment

Prism Doesn't Color White Light

Newton performed a crucial experiment to show that the prism wasn't coloring the light. He isolated a single color from the spectrum and passed it through a second prism.

The color remained unchanged, proving that the prism wasn't adding color but merely separating the colors already present in white light.

Recombination of Light

Newton's Recombination Experiment

Newton demonstrated that the spectrum colors could be recombined to form white light again. He used a lens to focus the dispersed colors back together.

This recombination experiment was crucial in proving that colors are components of white light rather than modifications of it.

Invisible Spectrum

The Invisible Spectrum

Beyond the visible spectrum lie invisible forms of electromagnetic radiation. These include ultraviolet (beyond violet) and infrared (beyond red).

The electromagnetic spectrum extends from very short gamma rays to very long radio waves, with visible light occupying only a tiny portion of this spectrum.

Infrared Radiation

Infrared Discovery

Discovered by William Herschel in 1800, infrared radiation lies just beyond the red end of the visible spectrum. Herschel used a thermometer to detect this "invisible light" which produced heat.

Infrared has wavelengths longer than visible light (700nm-1mm) and is associated with thermal radiation emitted by objects at room temperature.

EM Spectrum

Electromagnetic Spectrum

The complete EM spectrum includes (from short to long wavelength): gamma rays, X-rays, ultraviolet, visible light, infrared, microwaves, and radio waves.

All these are forms of electromagnetic radiation differing only in wavelength and frequency, but all travel at the speed of light in a vacuum.