Biological examples of a Biot-Savart law in magnetostatics?

[MarkTheQuark]

Hello everyone,

So, I was wondering, the Biot-savart show us a magnetic field created by a constant electric current. Initially I thought that an example would be biological systems with a nervous system that works on the basis of electrical discharges, but I don't think it's a valid example anymore.
Does anyone know some example of biological application of this law in magnetosthatics?

 

[kuruman]

First of all Biot-Savart more generally expresses the contribution to the magnetic field of current $I$ running in length element $d\mathbf{l}$. The current need not be constant. To a good approximation, there will be an instantaneous magnetic field value corresponding to an instantaneous value of the current.

That said, your initial thought is correct. Read about magnetoencephalography (MEG) here. This is but one link. There are more if you care to look further. I would have posted sooner had I seen this earlier.

 

[berkeman]

Read about magnetoencephalography (MEG) here.

Thanks for the link; it was very interesting.

BTW, remember the movie "Brainstorm" where the Industrial Designer says "Nobody is going to put a thing like that on their head!" and then proceeds to redesign it to make it look way better? That's what I thought of when I saw this image at that link:

 

[kuruman]

I never saw "Brainstorm". However, I do remember hearing a talk in the mid-seventies by a NYU researcher (I forgot his name) about this when it was in the embryo stage before . They were measuring spatial changes in magnetic field signals produced by the human brain. SQUIDs were not readily available then, so they fashioned two Helmholtz coils wired antiparallel to each other. In this configuration they were able to measure the gradient of the local magnetic field. I don't remember much else from the talk except that they ran their experiments around 3:00 a.m. because they had to wait for the NYC subways to stop running. The equipment was sensitive enough to pick up subway signals from several blocks away. This thread brought this all back.

 

[berkeman]

I never saw "Brainstorm".

I recommend it as an interesting film. It was pretty thought provoking for me many years ago:

https://en.wikipedia.org/wiki/Brainstorm_(1983_film)

Brainstorm is a 1983 American science fiction film directed by Douglas Trumbull, and staring Christopher Walken, Natalie Wood (in her final film role), Louise Fletcher, and Cliff Robertson.[1]

The only downer for me was that it was Natalie's last film. Sad, but a very nice and smart performance by her...

 

[berkeman]

Hello everyone,

So, I was wondering, the Biot-savart show us a magnetic field created by a constant electric current. Initially I thought that an example would be biological systems with a nervous system that works on the basis of electrical discharges, but I don't think it's a valid example anymore.
Does anyone know some example of biological application of this law in magnetosthatics?

So Mark, help us out here. What aspects of magnetic fields in biology are you asking about? Are the replies so far helpful, or are you more interested in things like homing pigeons or electric eels?

https://www.science.org/doi/10.1126/science.7280697

https://en.wikipedia.org/wiki/Electric_eel