Inside a nuclear fusion research tokamak, alpha particles (He2+\text{He}^{2+}He2+ nuclei) are produced with high kinetic energies. One such alpha particle travels with a velocity of 1.5 Mm s−11.5\ \text{Mm s}^{-1}1.5 Mm s−1 perpendicular to a magnetic field of flux density 2.5 T2.5\ \text{T}2.5 T that confines the plasma.
What is the magnitude of the magnetic force acting on this alpha particle? (The elementary charge e=1.6×10−19 Ce = 1.6 \times 10^{-19}\ \text{C}e=1.6×10−19 C)
6.0×10−13 N6.0 \times 10^{-13}\ \text{N}6.0×10−13 N
1.2×10−15 N1.2 \times 10^{-15}\ \text{N}1.2×10−15 N
1.2×10−12 N1.2 \times 10^{-12}\ \text{N}1.2×10−12 N
2.4×10−12 N2.4 \times 10^{-12}\ \text{N}2.4×10−12 N