Content:
- Definition
- How is the Lorentz force directed
- Application
- Conclusion
Definition
When electrons move along a conductor, a magnetic field arises around it. At the same time, if you place a conductor in a transverse magnetic field and move it, an EMF of electromagnetic induction will arise. If a current flows through a conductor that is in a magnetic field, the Ampere force acts on it.
Its value depends on the flowing current, the length of the conductor, the magnitude of the magnetic induction vector and the sine of the angle between the lines of the magnetic field and the conductor. They are calculated by the formula:
The considered force is partly similar to that considered above, but acts not on a conductor, but on a moving charged particle in a magnetic field. The formula is:
Important! The Lorentz force (Fl) acts on an electron moving in a magnetic field, and on a conductor - Ampere.
From the two formulas it can be seen that in the first and second cases, the closer the sine of the angle alpha is to 90 degrees, the greater the effect on the conductor or the charge Fа or Fl, respectively.
So, the Lorentz force does not characterize the change in the magnitude of the velocity, but the effect of the magnetic field on a charged electron or positive ion. When exposed to them, Fl does not perform work. Accordingly, it is the direction of the speed of movement of the charged particle that changes, and not its value.
As for the unit of measurement of the Lorentz force, as in the case of other forces in physics, such a quantity as Newton is used. Its components:
How is the Lorentz force directed
To determine the direction of the Lorentz force, as with the Ampere force, the left-hand rule works. This means, in order to understand where the value of Fl is directed, you need to open the palm of your left hand so that in the hand entered the lines of magnetic induction, and the extended four fingers indicated the direction of the vector speed. Then the thumb, bent at right angles to the palm, indicates the direction of the Lorentz force. In the picture below, you can see how to determine the direction.
Attention! The direction of the Lorentz action is perpendicular to the motion of the particle and the lines of magnetic induction.
In this case, to be more precise, for positively and negatively charged particles, the direction of the four extended fingers matters. The above left-hand rule is formulated for a positive particle. If it is negatively charged, then the lines of magnetic induction should be directed not towards the open palm, but towards its back, and the direction of the vector Fl will be opposite.
Now we will tell in simple words what this phenomenon gives us and what real effect it has on the charges. Let us assume that the electron moves in a plane perpendicular to the direction of the lines of magnetic induction. We have already mentioned that Fl does not affect the speed, but only changes the direction of motion of the particles. Then the Lorentz force will have a centripetal effect. This is reflected in the figure below.
Application
Of all the spheres where the Lorentz force is used, one of the largest is the movement of particles in the earth's magnetic field. If we consider our planet as a large magnet, then the particles that are near the north magnetic poles make an accelerated spiral motion. As a result, they collide with atoms from the upper atmosphere, and we see the northern lights.
However, there are other cases where this phenomenon applies. For example:
- Cathode ray tubes. In their electromagnetic deflection systems. CRTs have been used for more than 50 years in a row in devices ranging from the simplest oscilloscope to televisions of all shapes and sizes. It is curious that in matters of color reproduction and work with graphics, some still use CRT monitors.
- Electrical machines - generators and motors. Although here the force of Ampere is more likely to act. But these quantities can be considered as contiguous. However, these are complex devices during the operation of which the influence of many physical phenomena is observed.
- In charged particle accelerators, in order to set their orbits and directions.
Conclusion
Let's summarize and outline the four main theses of this article in simple terms:
- The Lorentz force acts on charged particles that move in a magnetic field. This follows from the basic formula.
- It is directly proportional to the speed of a charged particle and magnetic induction.
- Does not affect particle speed.
- Affects the direction of the particle.
Its role is quite large in the "electrical" areas. The specialist should not lose sight of the basic theoretical information about the fundamental laws of physics. This knowledge will be useful, as well as those who are engaged in scientific work, design and simply for general development.
Finally, we recommend watching useful videos to consolidate the studied material:
Now you know what the Lorentz force is, what it is equal to and how it acts on charged particles. If you have any questions, ask them in the comments below the article!
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