Medan Magnet oleh Arus Listrik - Fisika Kelas XII

Introduction

In this tutorial, we'll explore how electric currents create magnetic fields, a fundamental concept in physics. We will discuss the Biot-Savart law, the formula for calculating magnetic fields, and provide examples to clarify these concepts. Understanding these principles is crucial for grasping electromagnetism in physics classes.

Step 1: Understanding Magnetic Fields Around Electric Currents

• When an electric current flows through a wire, it generates a magnetic field around it.
• The direction of the magnetic field can be determined using the right-hand rule:
  • Point your thumb in the direction of the current flow.
  • Curl your fingers around the wire. The direction your fingers curl indicates the direction of the magnetic field lines.

Step 2: Learning the Biot-Savart Law

• The Biot-Savart law helps calculate the magnetic field generated by a segment of current-carrying wire at a point in space.
• The formula is expressed as follows:

B = (μ₀/4π) * (I * dl x r) / r²

Where:

• B is the magnetic field.

• μ₀ is the permeability of free space (4π x 10⁻⁷ Tm/A).

• I is the current in amperes.

• dl is the infinitesimal segment of the wire.

• r is the distance from the wire to the point where the field is measured.

• To apply this formula:

  • Identify the current (I) and the length of the wire segment (dl).
  • Determine the position vector (r) from the wire to the point of interest.
  • Calculate the cross product (dl x r) to find the direction of the magnetic field.

Step 3: Practical Applications and Examples

• To illustrate the Biot-Savart law, consider the following example:
  • Calculate the magnetic field at a point 0.1 m from a straight wire carrying a current of 5 A.

1. Use the Biot-Savart law:

   • Set I = 5 A.
   • Use dl = 1 m (assuming a straight wire segment).
   • Calculate r = 0.1 m.

2. Substitute values into the formula:

B = (4π x 10⁻⁷ / 4π) * (5 * 1 x 0.1) / (0.1)²

3. Simplify to find B.

• Common pitfalls:
  • Ensure the units are consistent (meters, amperes).
  • Remember to use the right-hand rule to determine the direction of the magnetic field correctly.

Conclusion

In this tutorial, we covered the essential concepts of how electric currents create magnetic fields, focusing on the Biot-Savart law and its applications. Understanding these principles is key to further studies in electromagnetism. As a next step, practice solving more examples using the Biot-Savart law to reinforce your understanding.