Search Coil Experiment (measure magnetic field strength)

Summary

In this video, the presenter demonstrates an experiment to measure the magnetic flux density of a magnet using a search coil, which is connected to a picoscope for EMF readings. The experiment compares this method with results obtained using a current balance method. The presenter describes the setup, calculation methods, and Faraday’s law application for determining flux density by analyzing the area under the peak of the voltage-time graph. Measurements of the coil's properties are also discussed, along with the process of capturing accurate readings to calculate the magnetic flux density.

Takeaways

• 🔬 The experiment aims to determine magnetic flux density using a search coil and compare it with a previous current balance method.
• 🔄 The search coil has 5,000 turns and a small cross-sectional area, used to measure induced EMF when placed in a magnetic field.
• 📊 The coil is connected to a picoscope, an oscilloscope that reads the EMF changes as the coil moves near a magnet.
• 📈 By quickly pulling the coil out of the magnetic field, a sharp peak in EMF is observed, which will be analyzed to calculate flux density.
• 🧮 The area under the EMF peak represents EMF multiplied by time (voltage vs. time graph), essential for determining flux density using Faraday's law.
• ⚖️ The key measurements required include the number of turns (N) and the coil's cross-sectional area, measured using a digital vernier caliper.
• 🗂️ The researcher uses the triangle area formula (1/2 base times height) to approximate the area under the EMF peak and ensure accurate flux density calculations.
• 📌 The experiment involves calculating the difference in voltage and time at key points to determine the triangle's base and height for analysis.
• 💻 The data collected will be saved and analyzed in a spreadsheet to calculate the magnetic flux density.
• 📽️ A follow-up video will show the analysis and comparison of the results from the search coil and the current balance method.

Q & A

What is the purpose of the experiment described in the video?

The purpose of the experiment is to determine the magnetic flux density of a magnet using a search coil and to compare the results with a previous experiment conducted using the current balance method.

What is a search coil, and how does it work in this experiment?

A search coil is a small, tightly bound coil with 5,000 turns. In this experiment, it is used to measure the induced EMF as it is moved through the magnetic field. The EMF data is then analyzed to determine the magnetic flux density.

How does the oscilloscope (Picoscope) contribute to the experiment?

The Picoscope, connected to the search coil, measures and displays the induced EMF as the coil moves through the magnetic field. This EMF is then analyzed over time to calculate the area under the peak, which is key to determining the magnetic flux density.

What key measurements are taken in this experiment to calculate the magnetic flux density?

The key measurements include the EMF induced in the coil, the time over which the EMF changes (delta T), the number of turns in the coil (N), and the cross-sectional area of the coil. These values are used in the equation derived from Faraday's Law to calculate the magnetic flux density.

How is Faraday's Law used in this experiment?

Faraday's Law states that the induced EMF is equal to the rate of change of magnetic flux linkage over time. In this experiment, the rearranged equation EMF × delta T = N × B × A is used, where B is the magnetic flux density and A is the cross-sectional area of the coil.

What tool is typically used to measure the cross-sectional area of the search coil, and why is it important?

A digital vernier caliper is typically used to measure the diameter of the search coil, allowing for the calculation of its cross-sectional area. This area is essential for determining the magnetic flux density as it factors into the equation for flux linkage.

What technique is used to analyze the EMF peaks from the oscilloscope readings?

The EMF peaks are analyzed by zooming in on the peak, approximating it as a triangle, and calculating the area under the peak using the triangle formula (1/2 base × height). This area is key for determining the flux density.

How does the experimenter ensure the peak is accurately measured despite curvature in the readings?

The experimenter eliminates the curvature by selecting points on the peak that most closely approximate a triangle, calculating the base and height, and then using this information to accurately determine the area under the peak.

What comparison will be made after completing this search coil experiment?

After completing the search coil experiment, the results will be compared to those obtained in a previous experiment using the current balance method to determine the magnetic flux density.

Why is it important to pull the search coil out of the magnetic field quickly during the experiment?

Pulling the search coil out of the magnetic field quickly ensures that a sharp EMF peak is produced, which can be accurately analyzed to determine the magnetic flux density.