In a magnetic confinement fusion reactor, an alpha particle (He2+\text{He}^{2+}He2+) escapes the core and enters a diagnostic region containing a uniform magnetic field. The magnetic flux density in this region is 850 mT850\text{ mT}850 mT.
What is the magnitude of the magnetic force acting on the alpha particle when its velocity is 4.5 × 103 km s-1 perpendicular to the magnetic field? (The elementary charge is e=1.6×10−19 Ce = 1.6 \times 10^{-19}\text{ C}e=1.6×10−19 C)
1.2×10−15 N1.2 \times 10^{-15}\text{ N}1.2×10−15 N
6.1×10−13 N6.1 \times 10^{-13}\text{ N}6.1×10−13 N
1.2×10−12 N1.2 \times 10^{-12}\text{ N}1.2×10−12 N
1.2×10−9 N1.2 \times 10^{-9}\text{ N}1.2×10−9 N