Guide
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For example, you need to solve this problem.An electron moving in a uniform magnetic field with the value of the induction B, while describing an ideal circular path.In a Lorentz force Fl.Centripetal acceleration electron is "a".We need to calculate the speed movement electron .
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To begin remember that this Lorentz force and how it is calculated.It is a force with which the electromagnetic field acts on a single charged particles.In your case, under the terms of (the electron is in a magnetic field, it moves in a circle of constant radius), the Lorentz force will be the c
entripetal force and is calculated as follows: Fl = evB.Fl and B values ​​given to you under the terms of the problem, the magnitude of the charge of an electron e easily found in any book.
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On the other hand, the Lorentz force (as well as any other force) can be expressed by the formula: Fl = ma.The mass of the electron m is also easy with the help of reference books.
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equating these expressions, you will see that evB equals ma.The only unknown to you the value - the same speed v, and you need to find.By elementary transformation, you get: V = ma / eB.Substituting in the formula known to you the magnitude (how the data under the terms of the problem, and found yourself), get an answer.
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Well, what about, for example, if you do not know either the magnitude of the induction B or the Lorentz force Fl, and instead given a circle radius r, on which the electron spins the same?How, then, to determine its speed ?Remember the formula for centripetal acceleration: a = v2 / r.From: v2 = ar.After extracting the square root of the product of the centripetal acceleration and the radius of the circle, and you get the desired speed electron .