# Magnetic Field Strength Formula

The magnetic field intensity is expressed in terms of Magnetic flux density (B) and Magnetic field strength (H), which are measured in Newton-metre per ampere (N-m/A) or Tesla (T) and Amperes per metre (A/m) respectively. The magnetic field lines can be assumed as the magnetic field lines that has close similarity to the field of the lines termed as density of these field lines. The total number of field lines passing through an area is known as magnetic flux density (measured in $T. m^{2}$).

The magnetic field density increases with the closeness of the distance from a straight current carrying wire, which means they are inversely proportional to each other.

In a given location of the current-carrying wire,

$Magnetic \;\; field \;\;density (B) \propto Current\;\; (in \;\; Amperes )$

#### Practise This Question

The normal of the curve x=d(cos θ+θ sin θ)y=a(sin θθ cosθ) at any θ is such that

[DCE 2000; AIEEE 2005]