Study of the Biot-Savart Law for a Coil

Concepts Covered in This Activity

✔ Magnetic field and electric current: Understanding how a current-carrying coil creates a magnetic field

✔ Biot-Savart Law: Relationship between current intensity and magnetic field strength in a coil

✔ Using a magnetometer: Measuring and analyzing an invisible physical quantity

✔ Graphical representation of experimental data: Observing the relationship between two physical quantities and verifying a theoretical law

Student Experiment Steps

🔹 Prepare the setup: Connect a coil to a variable power supply and position the smartphone in front of the coil

🔹 Activate the magnetometer: Measure the Y-component of the magnetic field generated by the coil

🔹 Vary the current intensity: Adjust different current values and record the corresponding magnetic field measurements

🔹 Create a data table: Record the measured values as a function of current intensity

🔹 Plot a graph: Represent the Y magnetic field as a function of current intensity and analyze the trend

🔹 Compare with theory: Verify if the obtained relationship follows the Biot-Savart Law and draw conclusions

Scientific Explanation for Teachers

1. Magnetic Field Created by a Coil

When an electric current flows through a coil, it generates a magnetic field proportional to the current intensity and the number of turns. This principle is the foundation of many devices, such as electromagnets and transformers.

2. Biot-Savart Law

The Biot-Savart Law describes the intensity of the magnetic field B created by an electric current. For a long coil, the magnetic field at its center is approximately given by:

B=μ₀⋅N⋅I/L

Where:

• B is the magnetic field intensity (in teslas)

• I is the electric current intensity (in amperes)

• N is the number of turns in the coil

• L is the coil's length

• μ₀ is the magnetic permeability of free space

The relationship between the magnetic field and current intensity is linear, which students can verify experimentally.

3. Smartphone Magnetometer

The smartphone’s magnetometer allows direct measurement of the magnetic field without external instruments. The Y-component is particularly useful, as it shows the field variation as the current changes.

4. Practical Applications

This experiment helps students understand the working principles of electromagnets, electric motors, and transformers, all based on the same physical laws.

This activity provides an experimental approach to the connection between electricity and magnetism, combining hands-on manipulation, measurement, and mathematical modeling of the phenomenon.