Atom and Electron
Atom and Electron
As I mentioned in the “Interesting Story about Light Science” Vol. 1, when the size of apple on a desk was enlarged by the size of the earth, an atom has same size as the apple on the desk.
Let me explain about atom in detail. Every atom is composed of a nucleus and one or more electrons bound to the nucleus. It is an axis in which electrons rotate around the nucleus. This is structurally similar to the earth’s orbit around the sun. 
What is the actual size of the atom? Atoms are extremely small; typical size of them is around 100 picometers (~10-10m). Moreover, the radius of a nucleus is approximately equal to 1 femtometers (~10-15m). When you expand an atom to the size of your living room, the atomic nucleus is about the size of a very small pinhole in the living room floor. The atom is made of empty space between the nucleus and the electron. Thus, when we take this empty space (vacuum) from human body which is composed of atoms, the actual volume of human body can be compared to the size of NaCl (~0.1mm). 

As I explained in the “Interesting Story about Light Science” Vol. 6, “Photon and Electron”, Huge amount of photons as 1x1018 per second is emitted from indoor lighting. When the photon strike an objects consist of atoms, then an electrons will be emitted by collision. Also, the higher the intensity of the emitted light, the more electrons will emit. When we shed light which have a relatively high energy (for example, blue light) on the object for a long time, the object may look discolored or broken. So, we need a safe light source, a light with minimal blue light.

Sooyoung Moon, Ph D.
Our Healthcare Committee

Next week’s topic: Spectral Distribution of Natural Sunlight

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