The dimension of $\frac{{ϵ}_0{E}^2}{2}$, ${\epsilon }_0$: permittivity of free space, $E=$ electric field) is

The time dependence of a physical quantity is given by $p=p_0{e}^{-\alpha t^2}$ where $\alpha$ is a constant and $t$ is time. The constant $\alpha$

The refractive index of a material is given by the equation $n=A+\frac{B}{{\lambda }^2}$, where $A$ and $B$ are constants.The dimensional formula for $B$ is