A 2 MeV proton is moving perpendicular to a uniform magnetic field 2 .5 T. The force on the proton is
2.5x10-10N
8x10-11 N
2.5 x10-11 N
8 x10-12 N
12mv2=2×106eV=2×106×e joules ∴ v=4×106×em1/2F=evB=eB4×106×em1/2=1.6×10−19(2⋅5)4×106×1.6×10−191.67×10−271/2=8×10−12N