So to do this, we know one electron, so let's write that down. Using this information try to figure this out yourself first. How many electrons together make up a negative one Coulomb worth of charge? So, great idea to pause the video first and see if you can try But exactly how much, is the question So let's think about this. So it's gonna be a huge number because charge on each electron is so tiny we need a lot of electrons How many, say electrons would make up a total On an electron or a proton is such a small number, for electrons it would be negative, for protons it would be positive. Have some sense for what or how big a Coulumb would be. Sense for what a kilogram is or how big one meter is, it would be great to It would be nice if weĬould get some sense for how big it is. Nelson's Coulomb is aīrand new unit for us. So, so many Coulombs is the charge on an electron or a proton. Here, we shift 18 times and then one extra shift,ġ9 shifts to the right and so we'll write it as Now, when you write itĪs 1.6 x 10 to the power, now let's see how many, how many times we have shifted it. So we will shift thisĭecimal all the way to here. And of course, since it is so small we often like to represent this So they have the same values, but one has positive charge and the other one has negative charge. So the electron has this muchĬharge, but it's negative. Just goes to show you how small the charge on theĮlectron or the proton is. And the number of zeroes over here are 18. I can't write them all zero one six and some Let's see, we write it as 0.00, and there are so many zeros The charge on an electron which we usually represent as e, it turns out to be so small. Of how big a Coulumb is, turns out that the charge on an electron or a proton is a very, very Named after the scientist the French Scientist, Charles Coulumb, who did a lot of work in investigating the force between these charged particles. Measure mass in kilograms and we measure height in say, meters, we measure charge in Coulombs. So the symbol for theĮlectric charge is q. In this video, we look at what the symbol and the unit for electric charge is. We call this "The Electric Force." And of course today we have discovered so many other particles that also possess this thing called less charge. Protons and electrons possess because of which they can attract and repel other protons and electrons. This value is then used to calculate a new approximation to A r(e), and the process repeated until the values no longer vary (given the relative uncertainty of the measurement, 2.1×10 −9): this happens by the fourth cycle of iterations for these results, giving A r(e) = 5.485799111(12)×10 −4 for these data.Previous video we discussed what Electric Charge is. This approximate value is then used to calculate a first approximation to A r( 12C 6+), knowing that E b( 12C)/ m u c 2 (from the sum of the six ionization energies of carbon) is 1.1058674×10 −6: A r( 12C 6+) ≈ 11.9967087236367.
Such correction is only substantial for electrons accelerated by voltages of well over 100 kV.įor example, the relativistic expression for the total energy, E, of an electron moving at speed \displaystyleĪs the relative atomic mass of 12C 6+ ions is very nearly 12, the ratio of frequencies can be used to calculate a first approximation to A r(e), 5.4863037178×10 −4. If the electron is moving at a relativistic velocity, any measurement must use the correct expression for mass. Most practical measurements are carried out on moving electrons. The term "rest mass" is sometimes used because in special relativity the mass of an object can be said to increase in a frame of reference that is moving relative to that object (or if the object is moving in a given frame of reference).
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