Question

The S.I. unit of magnetic field intensity is:
A. Webber
B. Tesla
C. Oersted
D. Gauss

Answer 1

- Hint: Magnetic field intensity also known as magnetic field strength. It is independent of material and dependent solely on magnetic field. It corresponds to the density of the magnetic field lines. It measures the intensity of the magnetic field.

Complete step-by-step solution -
A magnetic field is said to exist at a point if a force other than the electrostatic force, is exerted on a moving charge at that point. The force felt by the charged particle is given by,
$\overrightarrow{F}=q\overrightarrow{v}\times \overrightarrow{B}$
where, F is the force felt by the particle, q is its charge, v is the velocity with which it is moving and B is the strength of the magnetic field. From this we may write the magnitude of the field as,
$B={\displaystyle \frac{F}{qv\sin \theta }}$
The intensity of the magnetic field at a point is measured in magnitude and direction by the force on a unit north pole placed at that point. The S.I. unit of the magnetic field intensity will be,
$B={\displaystyle \frac{1N}{1C\times 1m{s}^{-1}}}=1N{A}^{-1}{m}^{-1}=1Tesla$
Hence, the S.I. The unit of magnetic field intensity is Tesla. Also, Tesla is related to Gauss as,
$1Tesla={10}^{4}Gauss$
While, the magnetic flux, which is the scalar product of magnetic field intensity and area is given by,
$\mathrm{\Phi }=\overrightarrow{B}\cdot \overrightarrow{A}$
It has an S.I. unit of Weber. Tesla can be written in terms of Weber as,
$1T=1Wb/m^2$
Thus, magnetic field intensity can be also defined as the flux density in the space.
Therefore, the correct option is B.

Note: Other than the magnetic field B, there is a medium independent term called the auxiliary field H, which in free space is the ratio of B and the permeability of the medium. It has a unit of Oersted.