Magnetic field's effect on a charged particle's motion

[agnwib]

Homework Statement

A positive charged particle moves in a homogeneous field with speed in direction north. Find the direction of the magnetic force on the particle when the magnetic field has direction to west.

Relevant Equations

I don't think there are any relevant equations

I actually have no idea how to begin. Thanks for help

 

[Doc Al]

Look up the Lorentz force law.

 

[agnwib]

Look up the Lorentz force law.

Hi, I looked it up, and I tried to use the right hand rule, but I don´t understand how to do it when I don´t know the direction of the power. I tried with the power having the direction "into the paper", and used the right hand rule, and then it worked, but I don´t know why. Can you please explain?

 

[Doc Al]

but I don´t understand how to do it when I don´t know the direction of the power.

What do you mean by "power"? You are given the directions of the charge's velocity and the magnetic field. That should be all you need to find the direction of the magnetic force on the charge.

Describe how you are using the right hand rule.

 

[agnwib]

What do you mean by "power"? You are given the directions of the charge's velocity and the magnetic field. That should be all you need to find the direction of the magnetic force on the charge.

Describe how you are using the right hand rule.

By "power" I meant the electric current. Normally, when I use the right hand rule I keep my thumb and index finger still, and bend the other fingers (middle finger, ring finger and pinky). Then I place the index finger in the direction of the electric current, the three bend fingers in the direction of the magnetic field and my thumb shows the direction of the magnetic force. I don´t know how to use this rule at this task because I don´t know the direction of the electrical current

 

[Doc Al]

I don´t know how to use this rule at this task because I don´t know the direction of the electrical current

In this problem there is only a single charge moving. That moving charge is the current.

 

[agnwib]

In this problem there is only a single charge moving. That moving charge is the current.

Okey, I understand. Does that mean that that when I use the right hand rule, the index finger should point to north (because the positive charged particle has valocity to that direction)? Because when I do this, I still get wrong answer.

 

[Doc Al]

Does that mean that that when I use the right hand rule, the index finger should point to north (because the positive charged particle has valocity to that direction)?

Yes, using your version of the right hand rule (which is OK).

Because when I do this, I still get wrong answer.

So, you have your index finger pointing north and your other fingers pointing west?

 

[salmanshu322]

The right hand rule states that: to determine the direction of the magnetic force on a positive moving charge, point your right thumb in the direction of the velocity , your index finger in the direction of the magnetic field (B), and your middle finger will point in the direction of the the resulting magnetic force

 

[Doc Al]

The right hand rule states that: to determine the direction of the magnetic force on a positive moving charge, point your right thumb in the direction of the velocity , your index finger in the direction of the magnetic field (B), and your middle finger will point in the direction of the the resulting magnetic force

There are many versions of the right hand rule. The one used by the OP is fine. (As is yours.)

Used properly, they all give the same answer.