x Turn on thread page Beta
 You are Here: Home >< Physics

# Solenoid Physics watch

need help to explain the effect!!
There is d.c. current passing through the coil.
And the coil starts moving in a SHM form.
However, I dont think it is a SHM as the acceleration varies.
Explanation plz !!!

It's a part of my coursework and the video is taken by myself.
Voltage: 15.3V
Initial current: 6.7A
It's an iron rod inside the coil.
2. (Original post by sirhcyin1)

need help to explain the effect!!
There is d.c. current passing through the coil.
And the coil starts moving in a SHM form.
However, I dont think it is a SHM as the acceleration varies.
Explanation plz !!!

It's a part of my coursework and the video is taken by myself.
Voltage: 15.3V
Initial current: 6.7A
It's an iron rod inside the coil.
What do you think the explanation might be?
*the magnetic field generated in the coil when a current flows in it
*the magnetic field induced in iron
*the attraction and repulsion of N and S poles
3. Those theories behind the experiment are already included in my write-up. However, the problem is that, I am not sure why the amplitude of oscillation varies with the time. Is it because of the change of magnetic force induced along the rod or other factors? What are the other factors?
4. (Original post by sirhcyin1)
Those theories behind the experiment are already included in my write-up. However, the problem is that, I am not sure why the amplitude of oscillation varies with the time. Is it because of the change of magnetic force induced along the rod or other factors? What are the other factors?
Have you studied electromagnetic induction. In particular Lenz's Law?
Moving coils and magnets generate emfs. (Faraday's Law.)
Take a look at (or search for) "eddy currents" and this will lead you to the explanation.
Here's a start
http://en.wikipedia.org/wiki/Eddy_current_brake

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: March 30, 2011
Today on TSR

### Unconditional offer...

But going to get a U!

### I work at the House of Commons, AMA!

Poll

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE