Is There a Better Way to Demonstrate Force on a Current-Carrying Wire?

[VitaminK]

Homework Statement

First, I had to look at how the number of turns in a coil affected the size of the induced ems (by approaching a bar magnet) .
Second, I had to look at how the speed of the bar magnet, approaching the coil, affected the induced ems.
Third, I had to look at which direction the induced current would have depending on the pole of the approaching magnet.

Relevant Equations

No equation

My question is if there is an alternative, maybe better, way of doing this?

 

[Gordianus]

Well...to the best of my knowledge, that's just what Faraday did. I firmly believe he was a smart guy.
Of course there are beautiful alternatives; here is a nice one:$$\nabla\times\vec E=-\frac{\partial\vec B}{\partial t}$$

 

[rude man]

To answer your stated question, you do need a magnetic field but you don't need a coil.
A metal bar moving in a stationary B field will also experience a generated emf and voltage. The voltage can be read with a voltmeter if its leads are not affected by the B field.

 

[DaveE]

Like this? Parallel bar demo
Or this? Rail gun demo

 

[rude man]

Like this? Parallel bar demo
Or this? Rail gun demo

Both these videos are intended to demonstrate force on a current-carrying wire by an external B field, not necessarily induction.

In the 1st demo there is induction only while the wires are in motion.

The rail gun is actually a pretty interesting example. Current is fed to the bar, resistance = r, by the external power supply = V. If the rail has zero ohms resistance then that current will be V/r.

BUT - as the bar begins to move, there is emf developed across the bar = Blv, l=bar length, v = velocity of bar. The induced emf thus builds up with speed which generates an opposing current to the power supply current in the bar.

When V = Blv there will be zero current in the bar and no further force is applied to the bar.

So we do have induction here, and it plays an important part. Force on the bar starts out at F = BlV/r but thanks to induction ends up at zero so it stops accelerating.

(I can't tell if his setup is exactly as I assumed; can't tell from the video.)

If there were no external power supply it would be a more basic demo of induction: move the bar along the rail; an emf is generated in the bar the same way = Blv.