# Formula: Induced Voltage due to Magnetic Field Change

## Induced voltage

Unit
This electric voltage is formed, for example, between the end points of a wire loop when the magnetic field $$B$$ penetrating the wire loop is changed. Notice: Only as long as the temporal change of the magnetic field happens, the induction voltage is measurable. As soon as the magnetic field is NOT changed ($$B$$ constant), the voltage at the endpoints of the conductor loop disappears.

If the conductor loop is short-circuited, i.e. the two contacts are connected, then an induction current $$I_{\text{ind}}$$ is generated in the conductor loop.

The minus sign in the induction law is justified by the Lenz rule in order not to violate the conservation of energy.

## Magnetic field change

Unit
Magnetic flux density $$B$$ enclosed by the conductor loop, which is changed by the value $$\Delta B$$. If this flux density $$B$$ changes in time, i.e. $$\Delta B \neq 0$$, then an induced voltage or induced current is generated in the conductor loop.

## Time span

Unit
This is a time span within which the magnetic flux density has changed by the value $$\Delta B$$. The smaller the time span within which the magnetic field has changed, the greater the induced voltage.

## Area

Unit
Area enclosed by the conductor loop. According to this formula, $$A$$ is not changed, i.e. in this case it is assumed that the area remains constant. This means: the conductor loop is not bent or manipulated in any other way to change the area penetrated by the magnetic field.

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