Light

Key concepts

How Light connects to the ideas, people and events around it.

1. Visible spectrum

   is part of

   The visible spectrum is the portion of the electromagnetic spectrum that human eyes perceive as color. It ranges from violet (~380 nm) to red (~750 nm).

2. Photon

   consists of

   A photon is a quantum of electromagnetic energy that exhibits both wave and particle properties. Visible light photons have energies between about 1.65 and 3.26 electronvolts.

3. Electromagnetic spectrum

   belongs to

   The electromagnetic spectrum encompasses all types of electromagnetic radiation, from radio waves to gamma rays. Visible light occupies a narrow band within this spectrum.

4. Isaac Newton

   studied by

   Isaac Newton was a 17th‑century physicist who demonstrated that white light can be split into a spectrum using a prism. His work laid the foundation for modern optics.

5. Thomas Young

   investigated by

   Thomas Young was an early 19th‑century scientist who performed the double‑slit experiment, revealing the wave nature of light. His interference experiments supported the wave theory over particle theories of his time.

6. Electric light

   used in

   The incandescent light bulb converts electrical energy into visible light by heating a filament. Thomas Edison’s 1879 design popularized electric lighting worldwide.

7. Photosynthesis

   drives

   Photosynthesis is the process by which plants convert light energy into chemical energy stored in glucose. Sunlight drives the light‑dependent reactions in chloroplasts.

8. Refraction

   experiences

   Refraction is the bending of light as it passes between media with different refractive indices. A common example is a straw appearing bent when immersed in water.

Questions about Light