# Magnetic force is a function of position?

1. May 11, 2007

### neelakash

Sir,can you tell me if magnetic forces are function of
position?Possibly,I read it somewhere in internet forums that magnetic
forces are functions of velocity.I have read in your QM book's first
page that---in microscopic level all type of force may be written as
-∂V/∂x...except magnetic forces.
Normally,forces are functions of position,velocity and time...I want
to know if the magnetic forces can be represented as function of
position only.I mean can we have a magnetic force depending on only
(x,y,z) and NOT their higher derivatives as well?

2. May 11, 2007

### ZapperZ

Staff Emeritus
Please refer to the Biot-Savart Law.

In addition, please do not start your post with "Sir". We have many women on this forum who are either physicists, or interested in physics, who could have answered your question.

Zz.

3. May 11, 2007

### Staff: Mentor

The magnetic field produced by a configuration of currents depends on position. It also depends on time if the currents vary with time.

The magnetic force that this field produces on a moving charge or current element therefore depends on position and time as described above, and on the velocity (b0th magnitude and direction) of the moving charge, or magnitude and direction of the current element.

4. May 11, 2007

### marlon

That's strange, you are asking about classical physics (ie the Lorentz force) yet you have been reading in a QM book ?

Your answer is this : the force exerted by a mangetic field B on a charged (q) particle is called the Lorentz force F = qv x B. The x means vector product ! Both velocity v (of the charged particle) and B depend on coordinates t (time), x,y and z, by definition. The force F therefore indeed depends on spatial coordinates and time t.

marlon

Last edited: May 11, 2007