1. Introduction to Magnetism: Magnetism is a fundamental force of nature, and it is closely related to electric currents. When an electric current flows through a conductor, it creates a magnetic field around it.
2. Ampere’s Right-Hand Rule: To determine the direction of the magnetic field around a straight current-carrying conductor, we use Ampere’s right-hand rule. Point your thumb in the direction of the current, and the curling of your fingers represents the direction of the magnetic field lines.
3. Field Strength: The strength of the magnetic field (B) produced by a straight conductor depends on the current (I) passing through it and the distance (r) from the conductor. The formula is given by: [B = \frac{{\mu_0 \cdot I}}{{2\pi \cdot r}}] Where:
4. Magnetic Field Lines: Magnetic field lines form closed loops around a current-carrying conductor. They emerge from the conductor’s side where the current flows out and re-enter on the opposite side.

• (B) is the magnetic field strength in Tesla (T).
• (\mu_0) is the permeability of free space ((4\pi \times 10^{-7} \, \text{T}\cdot\text{m}/\text{A})).
• (I) is the current in Amperes (A).
• (r) is the distance from the conductor in meters (m).

1. Direction of the Magnetic Field: The magnetic field produced by a straight conductor forms concentric circles around the conductor. It is perpendicular to the direction of current flow.
2. Magnetic Field Strength and Distance: The strength of the magnetic field decreases as you move farther away from the conductor. It follows an inverse relationship with the distance ((r)), meaning that doubling the distance will quarter the magnetic field strength.
3. Magnetic Field Inside and Outside the Conductor: Inside the conductor, the magnetic field is strongest and directly proportional to the current. Outside the conductor, the field is weaker but still follows the inverse relationship with distance.
4. Applications: Understanding the magnetic field due to current-carrying conductors is essential for the design of electromagnets, transformers, and various electrical devices.
5. Safety: Always exercise caution when working with electric currents and magnetic fields. Magnetic fields can affect nearby electronic devices and magnetic materials.
6. Summary: In summary, when electric current flows through a straight conductor, it creates a magnetic field around the conductor. The field’s strength depends on the current and distance from the conductor, and its direction follows the right-hand rule.

These notes should provide you with a basic understanding of the magnetic field produced by a straight current-carrying conductor, which is an important concept in the study of electromagnetism.

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