What is a Magnetic Field?

• A magnetic field is a region around a magnet or a current-carrying conductor where a magnetic force can be experienced.

• It’s invisible, but we can visualize it using magnetic field lines. These lines are imaginary curves that show the direction and strength of the magnetic field at different points.

Magnetic Field Around a Straight Conductor

• When an electric current flows through a straight conductor, it creates a magnetic field around it.
• The magnetic field lines form concentric circles around the conductor.

Direction of the Magnetic Field

• Right-Hand Thumb Rule:
  • Hold the current-carrying conductor with your right hand.
  • Point your thumb in the direction of the current flow.
  • Curl your fingers around the conductor.
  • The direction of your curled fingers indicates the direction of the magnetic field.

Strength of the Magnetic Field

• The strength of the magnetic field at a point depends on:
  • Magnitude of the current: A stronger current produces a stronger magnetic field.
  • Distance from the conductor: The closer you are to the conductor, the stronger the magnetic field.

Magnetic Field Formula

• The magnetic field (B) at a distance (r) from a straight, infinitely long current-carrying conductor is given by: B = (μ₀ * I) / (2πr) where:
  • B is the magnetic field strength in Tesla (T)
  • μ₀ is the permeability of free space (4π × 10^-7 T m/A)⁷
  • I is the current in Amperes (A)
  • r is the distance from the conductor in meters (m)

Applications of Magnetic Fields

• Electromagnets: Used in various devices like motors, relays, and transformers.

• Electric Motors: Convert electrical energy into mechanical energy.

• Generators: Convert mechanical energy into electrical energy.

• Magnetic Resonance Imaging (MRI): Used in medical diagnosis.