# Learn How to Calculate Magnetic Field Using Biot Savart Law - Tutorial

## How to Calculate Magnetic Field Using Biot Savart Law Equation - Definition, Formula and Example

##### Definition:

Biot-Savart law is an equation which narrates the magnetic field to the magnitude, direction, length, and proximity formed by an electric current and is used to work out the resulting magnetic field.

##### Formula:
Magnetic Field (B) = (μ0 / 4π) (Q v sinθ / r2)
###### Where,

μ0 = Permeability of a vacuum (4π x 10-7 N A-2) Q = Point Charge v = Velocity r = Distance θ = Angle between v and r

##### Example :

A point charge Q(50 A s) moving with velocity of 20 m/s creates a magnetic field due to current in wire. If a point P has a distance 30m from Q and is at an angle of 450 to its direction of motion. Calculate the magnetic field of current in wire.

##### Given,

Q = 50 v = 20 m/s r = 30m θ = 45o

##### To Find,

Magnetic Field of current in wire using Biot Savart Law Equation

##### Solution:

Substitute the given values in the formula,

 B = (μ0 / 4π) (Q v sinθ / r2) = (4π x 10-7 / 4π) ( (50 x 20 x sin 45o) / (30 x 30)) = 10-7 (707.107 / 900) = 0.786 x 10-7 N A-1 m-1