An $\alpha$-particle is describing a circle of radius $2 \mathrm{~m}$ with a certain speed in a field of magnetic induction $2 \mathrm{~T}$. The potential difference required to accelerate the particle, to that speed will be (the mass of $\alpha$-particle is $6.8 \times 10^{-27} \mathrm{~kg}$ and its charge is $3.2 \times 10^{-19}$ coulomb.)