The charged particle moving in a uniform magnetic field of (3 i +2 j ) T has an acceleration (4 i -x/2 j ) m / s^2. The value of x is

The charged particle moving in a uniform magnetic field of $\displaystyle (3 \hat{i}+2 \hat{j}) \mathrm{T}$ has an acceleration $\displaystyle \left(4 \hat{i}-\frac{x}{2} \hat{j}\right) \mathrm{m} / \mathrm{s}^2$. The value of $\displaystyle x$ is