Medan Magnetik • Part 1: Medan Magnet di Sekitar Kawat Berarus Listrik

Introduction

This tutorial provides a comprehensive overview of magnetic fields surrounding straight and circular current-carrying wires. It draws from the foundational concepts of electromagnetism, including how current affects magnetic fields and how to determine their direction using the right-hand rule. Understanding these concepts is essential for studying physics and engineering applications.

Step 1: Understanding Electromagnetism and Permeability

• Electromagnetism Basics: Electromagnetic fields are created by the flow of electric current. The strength and direction of the magnetic field depend on the current's magnitude and the distance from the wire.
• Permeability: This is a measure of how easily a material can support the formation of a magnetic field within itself. In practical terms, it affects how strong a magnetic field can become in a given material.

Step 2: Magnetic Field Around a Straight Current-Carrying Wire

• The magnetic field around a straight wire can be visualized using concentric circles centered on the wire.

• Formula for Magnetic Field (B): The magnetic field at a distance (r) from a long straight wire carrying a current (I) can be calculated using the formula

  [ B = \frac{\mu_0 I}{2\pi r} ] Where:
  • ( B ) is the magnetic field strength,
  • ( \mu_0 ) is the permeability of free space (approximately ( 4\pi \times 10^{-7} , T \cdot m/A )),
  • ( I ) is the current in amperes,
  • ( r ) is the distance from the wire in meters.

• Direction of the Magnetic Field: Utilize the right-hand rule:

  • Point your thumb in the direction of the current flow.
  • Your curled fingers show the direction of the magnetic field lines.

Step 3: Magnetic Field Around a Circular Current-Carrying Wire

• For a circular wire loop, the magnetic field is strongest at the center of the loop.

• Magnetic Field Formula for a Circular Loop: The magnitude of the magnetic field at the center of a circular loop is given by

  [ B = \frac{\mu_0 I}{2r} ] Where ( r ) is the radius of the loop.

• Direction of the Magnetic Field: Again, use the right-hand rule:

  • Curl your fingers in the direction of the current, and your thumb will point in the direction of the magnetic field.

Step 4: Problem Solving Example

• Example Problem: Determine the magnitude and direction of the magnetic field at a point near a straight wire and a circular loop.

  • Given: Current (I) = 5 A, Distance (r) from wire = 0.1 m, Radius (R) of loop = 0.05 m.

  Calculate B for the straight wire

  • Use the formula ( B = \frac{\mu_0 I}{2\pi r} ).

  Calculate B for the circular loop

  • Use the formula ( B = \frac{\mu_0 I}{2R} ).

• Determine Direction: Apply the right-hand rule for both scenarios.

Conclusion

In this tutorial, we've explored the basics of magnetic fields generated by current-carrying wires, including how to calculate their strength and direction. Understanding these principles is crucial for applications in electronics, physics, and engineering. For further learning, consider exploring more complex scenarios, such as the magnetic field in solenoids and toroids, as introduced in subsequent parts of the video series.