The dimensions of magnetic field in M, L, T and C (Coulomb) are given as

To find the dimensions of the magnetic field ($B$) in terms of mass ($M$), length ($L$), time ($T$), and charge in Coulombs ($C$), we can use the magnetic force formula acting on a moving charge.

The magnetic force ($F$) on a charge ($q$) moving with velocity ($v$) perpendicular to a magnetic field ($B$) is given by:
$F=qvB$

Rearranging the equation to solve for the magnetic field ($B$):
$B=\frac{F}{qv}$

Now, let's write the dimensions of each quantity on the right-hand side:
1. Dimension of Force, $\left[F\right]=\left[ML{T}^{-2}\right]$
2. Dimension of Charge, $\left[q\right]=\left[C\right]$
3. Dimension of Velocity, $\left[v\right]=\left[L{T}^{-1}\right]$

Substitute these dimensions back into the formula for $\left[B\right]$:
$\left[B\right]=\frac{\left[ML{T}^{-2}\right]}{\left[C\right]\left[L{T}^{-1}\right]}$

Simplifying the expression:
$\left[B\right]=\left[M{L}^{1-1}{T}^{-2-(-1)}{C}^{-1}\right]$
$\left[B\right]=\left[M{T}^{-1}{C}^{-1}\right]$

Therefore, the dimensions of the magnetic field are $\left[M{T}^{-1}{C}^{-1}\right]$.