# Right-hand rule question

1. Sep 25, 2008

### nuby

Why does the right-hand rule apply to both current in a wire and angular momentum in a gyroscope? Is there there a common denominator between the two effects?

2. Sep 25, 2008

### chroot

Staff Emeritus
Both rotation and the curl of magnetic fields are expressed using vectors which are perpendicular to the plane in which the rotation occurs. In any such situation, it is possible to define the perpendicular vector in two distinct ways. Thankfully, physicists long ago decided to use a single convention for all such decisions.

- Warren

3. Sep 25, 2008

### Antenna Guy

I think it is more accurate to say "perpendicular to the axis/vector about which the rotation occurs".

I'd agree that right-hand coordinate systems are the norm, but circular/elliptical polarization is still a two-handed convention within a one-handed system.

Regarding the gyroscope, if you use the "curl" of the fingers on your right hand to indicate positive rotation about the vector your thumb points in, you need only point your thumb in the opposite direction (or swap hands) to change the sign of the angular velocity of the gyroscope with respect to "the thumb". Handedness is only a convention - I wouldn't try to read more into it than that.

Regards,

Bill