Question

What is the unit of magnetic flux?
A. Dynes
B. Oersted
C. Gauss
D. Weber

Answer 1

Hint: The unit of magnetic flux can be found by using the units of magnetic field and area. We know that the magnetic flux is equal to the surface integral of the magnetic field. So the unit of magnetic flux can be found by multiplying the unit of magnetic field and area.

Complete step-by-step answer:
 The S.I. base units are also known as fundamental units. These include kilogram, second, Ampere, meter, Kelvin, mole, and candela. S.I units of all other physical quantities are derived from them.
We know that magnetic flux is integral to the magnetic field over area. So, mathematically we can write
$\phi =\int{B\cdot dA}$
The S.I. unit of area is
${{m}^{2}}$
The unit of magnetic field is
$kg{{s}^{-2}}{{A}^{-1}}$
So, unit of magnetic flux will be
$kg{{s}^{-2}}{{A}^{-1}}\times {{m}^{2}}=kg{{m}^{2}}{{s}^{-2}}{{A}^{-1}}$
 This unit is also called Weber
Therefore unit of magnetic flux is Weber
Hence the correct option is D.

Note: The S.I unit of magnetic flux was given the name Weber after the scientist Wilhelm Weber in honor of his contribution to physics. He along with Carl Gauss is credited for the invention of the first electromagnetic telegraph. Many other S.I. units are also named after other scientists in honor of their contribution to physics. For example, the S.I unit of magnetic field $\dfrac{kgm}{{{s}^{2}}}$ is called N in honor of the great scientist Sir Isaac Newton. S.I unit of frequency ${{s}^{-1}}$ is called Hz in honor of scientist Heinrich Hertz. Dimension of magnetic flux is
\[{{M}^{1}}{{L}^{2}}{{A}^{-1}}{{T}^{-2}}\]