Question

1. A uniform magnetic field is directed straight up, out of the page. Four charged particles (A,B,C,D) all travel with the same speed, but in different directions. The four cardinal directions (N, S, E, W) are all in the plane of the page. The particle types and directions of travel are given below. Rank the particles by the magnitude of the magnetic force acting on them from greatest to least.
2. A) particle: electron; direction: up, out of page;
3. B) particle: electron; direction: west;
   C) particle: proton; direction: east;
   D) particle: proton; direction: 45° north of east;

Answer 1

Magnetic force acting on a charged particle,

F = B*V*q Sin (@)

Since protons and electrons have same charge ,force depends only on angle between magnetic field and velocity.

Where, angle " @ " is in between the magnetic field and Velocity.

1) force equal to zero . Because velocity and magnetic field are in same direction (out of the page ) Sin( 0) = 0

2) Force directed the southward ( largest)

3) Force directed southward (largest)

4)Force directed towards 45 degree East of South, because the angle between magnetic field and Velocity is " 90degree" (Largest).You should notice that @ is the angle between magnetic field and Velocity .

Order is 4=3=2>1