Let's clear up these 3 crucial questions

[nix85]

There has been lots of debate about these but no conclusive answers so let's clear them up as they are essential to our OU RND.

1. DOES TESLA BIFILAR (PANCAKE OR SOLENOID) PRODUCE STRONGER FIELD COMPARED TO ORDINARY COIL OR NOT?

According to this vid, it does by ~30% which is a lot, but one guy below says he got no gain as did some here i think, while some claim they did however (synchro1).

https://www.youtube.com/watch?v=PxcS0oYsBG4

Have in mind, when winding bifilar or multifilar as a solenoid, there are two ways to do it,

a) different wires alternating on top of each other vertically and same wire on each level horizontally

b) the opposite of a)

In case you did not understand the difference just imagine a multifilar cable, you can wind it horizontally so each wire always ends on top of itself, or vertically so wires alternate on top of each other.

Also the question is if bifilar does provide field gain, does multifilar provide gain over bifilar?


2. DO WINDINGS OF A PANCAKE COIL FURTHER FROM THE CENTER CONTRIBUTE LESS TO THE FIELD IN THE CENTER OR NOT?

If we look at the formula for a field of a single loop we can see that it does.

B = u0 x I / 2R

To calculate the field strength in the center of pancake coil they integrate the value for all individuals coils that make it, obviously outer coils contributing less.

But isn't it logical flux from outer windings must pass through the center? Where else would it pass?

Has anyone measured the field and confirmed if outer windings contribute less to center field or not?

3. CAN ELECTROMAGNET IMMERSED IN THE FIELD OF A PERMANENT MAGNET NEUTRALIZE THE ATTRACTION AND HOW STRONG IT'S FIELD HAS TO BECOME?

If we place an electromagnet on top of a strong neodymium magnet (of course it's core gets fully permeated by the pm's field) and then we let current through the electromagnet in such direction that it's field opposes the pm how strong does the field of electromagnet have to be to neutralize it's attraction to PM?

Let's say PM's field is 0.5T, i assume electromagnet would have to produce 0.5T in opposite direction to cancel it's attraction and more than 0.5t to start to get repelled by the PM. But is this so?

What you think, have you tried this? I only have a small transformer electromagnet at the moment but i plan to perform this test.

[nix85]

Anyone?

[nix85]

To answer my own question, yes, outer loops contribute less to center flux density. Don't ask me why. So ideal electromagnet is neither pancake nor a long solenoid but a compromise.