Question: Dimensional formula of magnetic flux is: [PMT/NEET-1989]
a. $ML^{2}T^{-2}A^{-1}$
b. $ML^{0}T^{-2}A^{-2}$
c. $M^{0}L^{-2}T^{-2}A^{-3}$
d. $ML^{2}T^{-2}A^{3}$

Solution
Magnetic flux $\phi = B \times A$.
Magnetic field $B = \dfrac{F}{qv}$.

$
B = \frac{MLT^{-2}}{(AT)(LT^{-1})} = M T^{-2} A^{-1}
$

Now,
$
\phi = B \times A = (M T^{-2} A^{-1})(L^{2}) = M L^{2} T^{-2} A^{-1}
$

Answer
a. $ML^{2}T^{-2}A^{-1}$