Learn the Right hand Rules???

[ahs4n]

I've never gotten the right hand rule and it seems to always be on atleast one or two yestions on PS so can anyone help me with a site for tutorial or just help me understand it?

Thanks so much

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[Sharka]

There was one on the 5/2 test except it was for an electron so technically it was the left-hand rule.

 

[Sharka]

F=q(v x B)
where F is the magnetic force on a moving charged particle, v is the velocity of the moving particle, and B is the magnetic field. Notice that these are all vectors (except the charge, q) and all have directions in which you can use the right hand rule for. Remember that the right hand rule is only for MAGNETIC forces and the force vector is for a (+) charge only (negative charge is reverse). As you can tell by the equation, the particle must have a charge and be moving in order to have a force on it.

http://commons.wikimedia.org/wiki/File:Right_Hand_Rule_vBF2.PNG

Just match up the respective vectors to find the direction of the force. Sometimes they give you the force and either the velocity or B field in which you have to find the last component.

 

[Segovia]

This is a decent breakdown:

http://www.youtube.com/watch?v=9Zy0VHBXxLU&feature=related

Alternatively, if the right hand rule is a troublesome concept, as it was for me, you can use unit vectors. If you use unit vectors i,j,k to and assign them to qv and B, you will never have to throw gang signs during the test, and you will never get one of these wrong again.

The downside is, it takes a couple of hours to learn this way, and most people prefer the right hand rule. Plus, you have to define a coordinate system and stick with it, but it is really not that bad. After practice, it takes about 10 seconds to answer using unit vectors no matter if the charge is negative or positive.

 

[Lola84]

I remember having needed this during the mcat.

Use the right hand for positive charge:
Thumb: direction of current or velocity
Straight fingers (except your thumb): direction of magnetic field
palm: direction of FB
dorsal side of hand: direction of FE

There supposedly isn't a left hand rule... but I use the my left hand for negative charge.

 

[Lola84]

oh ya.. .you also use your right hand for current and magnetic field.

If you point your thumb out and curl your fingers:
Thumb: direction of I
curled fingers: direction of B

 

[245399]

There was one on the 5/2 test except it was for an electron so technically it was the left-hand rule.

I dont remember that question at all... uh oh

 

[rockaction]

Like all concepts in physics and chemistry which involve rules or equations, I of course came up with sexual/dirty mnemonics or ways to remember them. My one for right-hand rule is no exception.

 

[PRodulous]

I dont remember that question at all... uh oh

ditto to that! During the test, I was pulling one of these....

 

[KiwiBruin]

Lola84's explanations are all that you need! =D