Dimensions of magnetic field intensity is: [PMT/NEET-1997]
a. $[M^{0}L^{-1}T^{0}A^{1}]$
b. $[MLT^{-1}A^{-1}]$
c. $[ML^{0}T^{-2}A^{-1}]$
d. $[MLT^{-2}A]$

Solution
Use Lorentz force on a current element:

$F = B\,I\,L \Rightarrow B = \dfrac{F}{I\,L}$.

Dimensions: $[F]=MLT^{-2}$,

$[I]=A$,

$[L]=L$.

Hence $[B]=\dfrac{MLT^{-2}}{A\cdot L}=MT^{-2}A^{-1}$,

i.e. $[M^{1}L^{0}T^{-2}A^{-1}]$.

Answer
c. $[ML^{0}T^{-2}A^{-1}]$