Question

A 5 MeV proton moves vertically downward through a magnetic field of induction 1.5 weber/m² pointing horizontally from south to north. The force acting on the proton, mass of proton = 1.6 × 10^–27 kg. will be-

(A) 7.44 × 10^–12 N 

(B) 3.1 × 10^–12 N 

(C) 5 × 10^–12 N 

(D) 6 × 10^–12 N

Answer 1

Correct option (A) 7.44 × 10^–12 N

Explanation:

Kinetic energy of the proton = 1/2 mv² = 5 meV

The magnetic field is horizontal from south to north and velocity vector v is vertically downward, i.e. angle between vector v and is vector B is 90º therefore force on proton

According to Fleming left had rule, the direction of force is horizontal from west to east.