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Faraday's Law

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Faraday's law state that the induced emf is the negative change in the magnetic flux per unit of time. Any change in the magnetic field or change in the orientation of the area of the coil with respect to the magnetic field induces a voltage (emf). The magnetic flux measures the number of magnetic field lines through a given surface area. Magnetic flux is estimated from the integral of the dot product of the magnetic field vector and the area vector. The negative sign describes the direction in...

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Related Experiment Video

Updated: Jun 12, 2026

A Silicon-tipped Fiber-optic Sensing Platform with High Resolution and Fast Response

A Silicon-tipped Fiber-optic Sensing Platform with High Resolution and Fast Response

Published on: January 7, 2019

Fiber optic tachometer based on the Faraday effect.

B J Zook, C R Pollock

|June 18, 2010

Summary

This summary is machine-generated.

This study introduces a fiber optic tachometer utilizing the Faraday effect for precise speed measurements. The novel design achieves high modulation depths and signal-to-noise ratios, enabling reliable remote sensing applications.

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Last Updated: Jun 12, 2026

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Area of Science:

Photonics
Magneto-optics
Sensing Technology

Background:

Traditional tachometers face limitations in harsh environments.
Fiber optic sensors offer advantages in electromagnetic immunity and remote operation.

Purpose of the Study:

To develop and characterize a novel fiber optic tachometer.
To leverage the Faraday effect for non-contact rotational speed measurement.

Main Methods:

Utilized a yttrium iron garnet (YIG) crystal as a magnetooptic modulator.
Employed a permanent magnet and a rotating toothed wheel to alter the magnetic field.
Modulated 1.3-microm light transmitted through a multimode fiber.

Main Results:

Achieved modulation depths up to 50%.
Obtained signal-to-noise ratios exceeding 15 dB.
Demonstrated a single multimode fiber connection for remote sensing.

Conclusions:

The developed fiber optic tachometer effectively measures rotational speed using the Faraday effect.
The system offers robust performance with high modulation and signal quality.
This technology is suitable for remote and demanding measurement applications.