# Best straightforward method to calculate the direction of the Lorentz force

• greg_rack

#### greg_rack

Gold Member
Hi guys, I'm being introduced to magnetism, and the direction of the Lorentz force is quite confusing since it's involving a vector product.
Which method would you recommend me in order to easily deduce the direction?

Can you write which formula you are having trouble with?

.. it's involving a vector product.
Which method would you recommend me in order to easily deduce the direction? From: https://en.wikipedia.org/wiki/Cross_product#Definition

But note that for negative charges the direction flips, so you can use the left hand.

• vanhees71 and greg_rack From: https://en.wikipedia.org/wiki/Cross_product#Definition

But note that for negative charges the direction flips, so you can use the left hand.
That's what I meant, thank you very much!

That's what I meant, thank you very much!
Alternatively, imagine the usual ##x-y## axes, with the x-axis pointing left to right across the page and the y-axis pointing up the page, then the z-axis is upwards from the page. And ##\vec x \times \vec y = \vec z##.

Last edited:
• Ibix, vanhees71 and greg_rack
That's what I meant, thank you very much!
Note that you can cycle the fingers used. I personally find this easier to remember:

thumb X index-finger = middle-finger

because it is the finger order I use in counting.

• vanhees71 and greg_rack