# What is the unit of magnetic flux

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### The magnetic flux

 This material was dealt with on January 20, 2005
(See Leisi, Classical Physics II [Lei98, pp. 138]) (See Tipler, Physik [Tip94, pp. 876])

In connection with the electric fields we had the electric flow introduced. Here we move the ladder loop with speed , We change the area through which the magnetic field flows by the size . Because the speed is, we can also write

 (4.300)

write. We define that
magnetic flux
 (4.301)

through the area

So that is the induced emf

 (4.302)

It is generated by the flow that changes over time.

The unit of magnetic flux is Weber.

 Weber (4.303)

The minus sign in the equations for the magnetic flux comes from the fact that a velocity is positive -Direction a reduction in the area causes.

 This material was dealt with on January 27, 2005
 materials

The magnetic field generated by the current is directed in such a way that the movement of the coil is braked. This behavior is reflected in the Lenz's rule summarized:

 The induction voltage and the current it causes are always directed in such a way that they counteract the cause.
 Comparison of a bar magnet with a coil.

A Kitchen sink creates an axial magnetic field. The direction of the magnetic field is with the Right hand rule derived from the direction of the current. A bar magnet generates the same magnetic field as a coil.

 The north and south poles of the magnets are defined as follows: The -Field lines run from the North Pole to the South Pole.
 Induced tension

If you move a magnet with the speed away from a bar magnet, this causes the Lorentz force a stream having a magnetic field induced. This magnetic field is directed in such a way that it is in the same direction as the magnetic field of the rod. The metal ring is attracted by the bar magnet and its movement to the right is braked (Lenz's rule).

 Sign of the magnetic field and the induced voltage when switching on and off.

A magnetic field is switched on here. The direction of the field lines is determined by the Right-hand rule certainly. A magnetic field in the right coil that increases over time is equivalent to a movement of the right coil in the inhomogeneous field (more intense on the left than on the right) to the left. The relevant field component points outwards. From the Right hand rule the specified current direction results. After switching off the exciting current, the intensity of the magnetic field decreases. This is equivalent to moving the right coil to the right, with the direction of the magnetic field remaining the same. The direction of the current is reversed accordingly.

 Self induction

When a current flows through a coil, it creates a magnetic field. If the current through the coil is changed, a voltage is induced which, as in the previous case, is directed in such a way that it counteracts the change in the magnetic field, including the change in the current flowing through the coil. In the special case that the current is switched off, i.e. that the resistance in the circuit increases by many orders of magnitude, a very high voltage is generated.

Applications

• Ignition coil in gasoline engines
• Generation of the acceleration voltage in television tubes