An electron is a tiny fundamental particle of negative charge. Find out about the size of an electron compared to an atom and a chromosome with help from an applied physics professional in this free video clip.

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An electron is a tiny fundamental particle of negative charge. Find out about the size of an electron compared to an atom and a chromosome with help from an applied physics professional in this free video clip.

Part of the Video Series: Such Great Physics

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Hello, my name is Walter Unglaub. And this is the size of an electron compared to an atom and a chromosome. An electron is a tiny fundamental particle of negative charge. And the truth is no one really knows how truly big an electron is. String Theory predicts that a size of an electron is on the order of a Planck length, which is approximately one times 10 the negative 35 meters. This is very small. Classically you can calculate the classical electron radius which we will denote as R sub E. And the electron radius classically is defined as one over four-Pi epsilon knot. Where epsilon knot is the permittivity of free space. Times the charge of the electron-squared, divided by the mass of the electron times the speed of light squared. So the classical radius or size of the electron in this case, would be approximately two point eight two times 10 to the negative 15th meters. Considerably larger than something that String Theory would predict. Now we just need to know the approximate sizes of an atom and a chromosome. So, one atom has the size on the order of an angstrom. Which is equal to one times 10 to the negative 10 meters. Whereas a chromosome, while the size can vary just like the size of an atom can vary. But the order of magnitude of an X chromosome is approximately seven micrometers or micrometers. This is equal to seven times 10 to the negative six meters. So, if we're interested in comparing the size of an electron to an atom and an X chromosome classically. Then we would use the classical radius. And for an atom compared to an electron, the atom would be 35,500 times larger than the electron. Whereas the X chromosome would be approximately two point five billion times larger than an electron. If we were to assume that the electron size is truly on the order of a Planck length, such as String Theory would predict. Then an atom would be approximately one times 10 to the 25 times larger. That's a one with 25 zeroes after it. And then, X chromosome would be on the order of one times 10 to the 30 times larger than an electron. So, that's a one with 30 zeroes trailing after it. So, five orders of magnitude larger than an atom. So, there is a considerable size difference between these different structures that make up matter and biological systems. Hello, my name is Walter Unglaub, and this is the size of an electron compared to an atom and a chromosome.