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 .
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.
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.
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.
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 .