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Geophonic Seismic Traces

Comparison between Geophone and Seismometer The three geophones we used for the construction of the Geophonic Seismometer are very sensitive instruments. Their natural frequency (mechanical resonance frequency) is about 4.5 Hz. At frequencies lower than 1 Hz the response is very attenuated, while it remains fairly constant even at higher …

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Geophonic Seismometer

Geophone In a series of previous posts we have described a horizontal pendulum seismometer: Horizontal Pendulum Seismometer Seismometer : Read-out Electronics Seismometer Traces The one described above is a seismometer with a medium-long period (about 5 sec) suitable for the detection especially of remote earthquakes (telesisms). Neighboring – and weak …

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Seismic Traces

In this post we describe the seismic monitoring activity carried out with the PhysicsOpenLab seismometer. The tool has been described in the posts : Horizontal Pendulum Seismometer, Seismometer : Read-out Electronics. The geographic position of our seismic station has the following data : Latitude : 46° 04′ 01” N (46.067 …

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Seismometer : Read-out Electronics

LVDT Sensor The seismometer position sensor is an LVDT type transducer (inductive displacement transducer). This transducer is an electrical device that allows the measurement of a linear displacement. The transducer is usually made of a tube with three windings arranged with parallel axes and with a mobile ferromagnetic cylindrical core …

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Horizontal Pendulum Seismometer

Introduction The seismometer is a fascinating tool that allows us to “closely” study the geophysics of the earth’s crust. As we know, the earth’s crust is subject to earthquakes which are nothing but vibrations of the rock layers that make up the lithosphere, produced by internal movements that occur underground. …

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Lock-in Amplifier

Introduction A lock-in amplifier (also known as a phase-sensitive detector) is a type of amplifier that can extract a signal with a known carrier from an extremely noisy environment. It is basically an analog multiplier followed by a low pass filter. Practically a lock-in amplifier convert the high frequency signal …

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Faraday Rotation

Introduction The Faraday effect or Faraday rotation is a magneto-optical phenomenon — that is, an interaction between light and a magnetic field in a medium. The Faraday effect causes a rotation of the plane of polarization which is linearly proportional to the component of the magnetic field in the direction of propagation. This effect occurs in most optically transparent dielectric materials …

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Right or Left ? Optical Activity & Chirality

Introduction In nature, the right and the left are NOT interchangeable. Chirality (a property of a rigid object that cannot be superimposed on its mirror image) was discovered by Louis Pasteur in 1848, studying the optical properties of a compound well known to oenologists, tartaric acid. Chirality is primarily a …

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Polarization of Light

We know that to experiment with light polarization it is necessary to have a rotatable support to hold the polarizing filter, such equipment are really expensive ! But everything changed when we found on eBay a simple rotatable platform for a robotic arm, the following picture shows the”gadget” (search online …

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Surface Plasmon Resonance

In the image above the evanescent wave excites the plasmon resonance on the surface of a thin layer of gold, the plasmonic wave is diffused and gives rise to the luminous red spot that can be seen on the prism. In this post we show how to carry out an experiment …

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