Direction of Magnetic Force in Relation to Electron Movement

[STEMucator]

Homework Statement

Just a quick question I had about finding the direction of a magnetic force.

I have abandoned my 2D way of thinking when it comes to these because perceptually it's completely wrong to think about it that way.

Lets say I have an electron moving with a constant velocity through a magnetic field.

Some relevant info will be provided below.

Homework Equations

$\vec{B} = 1.4T [Up]$
$\vec{v} = 5.00x10^6 m/s [North]$
$q_{electron} = 1.60x10^{-19}C$

The Attempt at a Solution

The magnetic force can be calculated:

$F_M = qvB = 1.60x10^{-14}N$

To find the direction of the magnetic force, the right hand rule can be applied. The electron is initially moving [North], so to be able to use my right hand to find the direction, I should initially point my thumb [South].

There is a magnetic field in the region in the [Up] direction, perpendicular to the motion of the atom. Using the right hand rule, my remaining fingers point in the [Up] direction.

I believe this will result in my palm pushing to the west, in the direction of the magnetic force.

Here's a drawing of how I'm visualizing the region:

http://gyazo.com/3846aa2d5e7826878ea69965d528da27

Would all of this be reasonable?

 

[UltrafastPED]

I get East for the direction; F = v x B gives a right handed coordinate system based on v, B, and F corresponding to i, j, k.

So if you align i with North, j with Up, k must be pointing East.

And when I use my right hand, thumb pointing north, index finger pointing up, my palm points east.

See http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/magfor.html

 

[STEMucator]

I get East for the direction; F = v x B gives a right handed coordinate system based on v, B, and F corresponding to i, j, k.

So if you align i with North, j with Up, k must be pointing East.

And when I use my right hand, thumb pointing north, index finger pointing up, my palm points east.

See http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/magfor.html

[East] is my original answer for the problem. My question is, why is the diagram I've drawn been so misleading then?

 

[UltrafastPED]

The diagram was too complicated and compacted for me to follow.

I simply sketched the field, the velocity, and the force as three perpendicular axes which obeyed the right hand rule ... simple is better?

 

[STEMucator]

The diagram was too complicated and compacted for me to follow.

I simply sketched the field, the velocity, and the force as three perpendicular axes which obeyed the right hand rule ... simple is better?

Simple is better.

You said this though:

And when I use my right hand, thumb pointing north, index finger pointing up, my palm points east.

Why point your thumb north? When I got my answer as [East] I used a slightly different method:

The thumb should extend south because an electron is being used and the initial velocity is north. The fingers will point into the page and the palm will push towards the east.

 

[UltrafastPED]

I forget that it was an electron; this just changes the sign on the force when you are done.

In that case the force is pointing West. This is same as you got in the OP.

 

[STEMucator]

I forget that it was an electron; this just changes the sign on the force when you are done.

In that case the force is pointing West. This is same as you got in the OP.

So the answer is actually west and not east?

 

[UltrafastPED]

I believe this will result in my palm pushing to the west, in the direction of the magnetic force.

I agree with your original answer: you got west!

 

[STEMucator]

I agree with your original answer: you got west!

Okay. So the force is actually pointing west.

There wasn't anything misleading about my interpretation then (the drawing)?

The NESW arrangement represents the "sheet of paper" if you will in the x-y plane and the "up" and "down" on the z axis represent "out of" and "into" the page respectively.