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- When they detect certain wavelengths of visible light, the photoreceptors trigger electrical signals. Rods and cones will send these signals through nerves that reach into the brain. They head for the occipital (Awe-SIP-ih-tal) cortex, right up against the back of the skull.
www.snexplores.org/article/explainer-how-our-eyes-make-sense-of-light
Classically, electromagnetic radiation consists of electromagnetic waves, which are synchronized oscillations of electric and magnetic fields. In a vacuum , electromagnetic waves travel at the speed of light , commonly denoted c .
A large body of literature exists on the response of tissues to electromagnetic fields, primarily in the extremely-low-frequency (ELF) and microwave-frequency ranges.
- 1993
- Reflection. Reflection is when incident light (incoming light) hits an object and bounces off. Very smooth surfaces such as mirrors reflect almost all incident light.
- Absorption. Absorption occurs when photons from incident light hit atoms and molecules and cause them to vibrate. The more an object's molecules move and vibrate, the hotter it becomes.
- Diffraction. Diffraction is the bending and spreading of waves around an obstacle. It is most pronounced when a light wave strikes an object with a size comparable to its own wavelength.
- Scatter. Scattering occurs when light bounces off an object in a variety of directions. The amount of scattering that takes place depends on the wavelength of the light and the size and structure of the object.
With a strong light source, red light can be transmitted through the hand or a fold of skin, showing that the red end of the spectrum is not absorbed as strongly as the violet end. While exposure to visible light causes heating, it does not cause ionization with its risks.
- Overview
- Electromagnetic Energy
- Sun & Atmosphere
- Beyond our Atmosphere
This article is about the Electromagnetic energy and its uses. It explains how electromagnetic energy travels in waves, spans a broad spectrum from radio waves to gamma rays, and how NASA's scientific instruments use it to study the Earth, solar system and universe beyond. The article also mentions that our atmosphere protects us from exposure to h...
Electromagnetic energy travels in waves and spans a broad spectrum from very long radio waves to very short gamma rays. When you tune your radio, watch TV, send a text message, or pop popcorn in a microwave oven, you are using electromagnetic energy. You depend on this energy every hour of every day. Without it, the world you know could not exist.
The Earth's atmosphere protects us from exposure to harmful higher-energy waves that can be ionizing and cause damage to cells in organic matter but is not helpful when studying sources of high-energy radiation in space as instruments have to be positioned above Earth's atmosphere.
NASAspacecraft provide scientists with a unique vantage point helping them "see" at higher-energy wavelengths that are blocked by the Earth's protective atmosphere while some microwaves can even pass through clouds making them best for transmitting satellite communication signals.
Prolonged exposure to high intensity or high energy (i.e. short wavelengths like UV and blue) light at certain levels can cause oxidative stress in our eyes, break down pigments, and even cause the death of photoreceptor cells. Many modern light bulbs have a strong blue light component.
Optical radiation includes ultraviolet, visible, infrared radiation. Most sunlight reaching the Earth’s surface is visible or infrared. Electromagnetic radiation (EMR) includes gamma rays, X-rays, ultraviolet radiation (UVR), visible light (VL), infrared (IR), microwaves, and radio waves (Figure 1).
