Magnetic Field Strength Can Be Calculated Using The Following Equation

The Magnetic Field Strength Formula

The magnetic field strength (B) produced by a long, straight current-carrying wire can be calculated using the Biot-Savart law, which simplifies to:

This formula shows that the magnetic field strength decreases with the square of the distance from the wire. It also increases with the current and is proportional to the permeability of free space.

How to Use the Calculator

Our magnetic field strength calculator provides a simple way to compute the magnetic field strength based on the current and distance from the wire. Here's how to use it:

1. Enter the electric current in Amperes (A)
2. Enter the distance from the wire in meters (m)
3. Click "Calculate" to compute the magnetic field strength
4. Review the result in Tesla (T)
5. Use the "Reset" button to clear the form

The calculator automatically uses the permeability of free space (μ₀ = 4π × 10⁻⁷ T·m/A) in its calculations. The result is displayed with appropriate scientific notation when needed.

Practical Examples

Let's look at some practical examples of calculating magnetic field strength:

Example 1: Small Current and Close Distance

If a wire carries 2 Amperes of current and we measure the magnetic field strength 0.1 meters from the wire:

B = (4π × 10⁻⁷ × 2) / (2π × 0.1) = 4 × 10⁻⁷ / 0.2 = 2 × 10⁻⁶ T

This is a very weak magnetic field, typical of small currents at close distances.

Example 2: Medium Current and Medium Distance

For a 10 A current and a distance of 0.5 meters:

B = (4π × 10⁻⁷ × 10) / (2π × 0.5) = 4 × 10⁻⁶ / 1 = 4 × 10⁻⁶ T

This is still a relatively weak field, demonstrating how quickly the field strength decreases with distance.

Example 3: Large Current and Far Distance

With a 100 A current and a distance of 1 meter:

B = (4π × 10⁻⁷ × 100) / (2π × 1) = 4 × 10⁻⁵ / 1 = 4 × 10⁻⁵ T

Even with a large current, the field strength remains relatively weak at this distance.