Electric and Magnetic Field Parallel

[navm1]

Homework Statement

Homework Equations

F=qE+qv x B

The Attempt at a Solution

The electric and magnetic fields are parallel, so the magnetic force will be in the j direction and the electrostatic force will be in the k direction. If the magnetic force was acting alone it would be cyclotron motion but since the electrostatic force is acting too does this mean it is moving in a helical path? I'm having some difficulty thinking about where the electric field is pointing and how to draw it properly. Thanks

for part b) I can find the acceleration using (qE)/m and plug into a distance equation but I am not sure if that is what I'm being asked to do.

 

[mfb]

If the magnetic force was acting alone it would be cyclotron motion but since the electrostatic force is acting too does this mean it is moving in a helical path?

Sort of helical, as it is always accelerating in k-direction.

 

[navm1]

Thanks. For part b, if I use v_0t+1/2*((qE/m))t^2 as the position of the proton along the z direction. Then for part c I can calculate the period and then put '3T' into the equation I found in part b to find the particles position. Am I on the right track with this?

 

[mfb]

For part b, if I use v_0t+1/2*((qE/m))t^2 as the position of the proton along the z direction.

What is v_0 in z direction?

Then for part c I can calculate the period and then put '3T' into the equation I found in part b to find the particles position. Am I on the right track with this?

Right.

 

[navm1]

What is v_0 in z direction?
Right.

v_0 in the z direction is 0 so z=1/2*((qE/m))t^2 = 1/2* ((1.6x10^-10)(5000))/1.673x10^-27)*(1.3x10^-4)^2 = 4041m = 4km ?

 

[mfb]

Is that the distance after one or after three revolutions?

 

[navm1]

my mistake, that is one revolution so three should be 36431metres

 

[mfb]

Right.