The 3-finger rule simply explained

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To determine the direction of the Lorentz force, there are several ways to proceed. The simplest and most well-known of these is the so-called "3-finger rule". This is easy to learn and easy to use.

The Lorentz force acts on current-carrying conductors in the magnetic field.
The Lorentz force acts on current-carrying conductors in the magnetic field.

The area of ​​application of the rule

  • The 3-finger rule is mainly used in electrical engineering - that is, in school subjects physics - used and is often used there. The three fingers, thumb, index and middle finger each represent a vector in an imaginary three-dimensional coordinate system.
  • By means of the rule, which is probably known to most from school lessons, one can find out the direction of the so-called Lorentz force. Generally speaking, the Lorentz force is the force that acts on a current-carrying conductor that is located in a magnetic field.
  • The 3-finger rule of the right hand is also known under the names UVW rule or IBF rule. In the IBF rule, the designations "I" stand for the current, "B" for the magnetic field and "F" for the Lorentz force (memory aid for students: "I am Franz").
  • If you want to use the 3-finger rule of the right hand, you always proceed according to the same scheme and generally follow the same procedure.

Rotate the 3 fingers correctly - this is how it works

With the 3-finger rule of the right hand, the thumb, index and middle finger are correct to hold each other in order to thereby use the middle finger in the direction of the so-called Lorentz force determine.

Electromotor principle simply explained

A physical law is known as the electromotive principle, which in ...

  1. Extend your right hand thumb upward. Now hold it in the direction of the current (technical direction of current, that is, the wrongly imagined movement of positively charged particles).
  2. Stretch in 90 °angle the index finger out to the thumb. Hold it in the direction of the field lines of the magnetic field. You can recognize this by the direction of the arrow. Do not change the direction of the thumb, otherwise the determined direction of the Lorentz force will be wrong.
  3. Then hold your extended middle finger at a 90 ° angle to the index finger. Do not change the direction of the first two fingers during this step either. If you have done everything correctly, the extended middle finger will now show you the direction of the Lorentz force.

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