# Sagnac effect - Real model

- Author:
- Max Born

Sagnac effect: Real model
Every fibre optic gyroscope (FOC) implements the sagnac effect. The path of the light is modelled by a circle. In the FOC the coil of fibres acts like a polygon with one mirror at each point. The

**time elapsed**during the passing of the two beams gives a measure of the**fringe shift**that may be detected when the whole apparatus is**rotating**. To change the time use the slider t, to change the rotational speed use the slider ß.Just learn about the sagnac effect when playing with the sagnac model.
Lessons to learn:
- There is a crossing of the two beams. Why?
- The higher the rotational speed the greater the total distance needed to meet the getter.
- In order to calculate the shift Delta-z the difference of travel time (t_L-t_R) is used. But this cannot be used as an explanatory solution. Why!
Have fun!