farmer1

Managed to work out the rest of the practical myself, but how on earth do you measure the amplitude of damped vibrations.

I was thinking of using a guitar type pick up, but as we are using a helmholtz coil to damp the sheet electromagnetically, this would interfere with the pick up coil.

I then thought that we could fix the osillations into a standing wave creating two anti nodes. One to damp and one to measure the amplitude of osillations.

What I need to find out is howlong it takes to dampen the osillations to halve the original amplitude. Is it possible to only dampen one anti node and then use the other to measure the osillations or will only damping one destroy the standing wave?

Alternatively does anyone have any suggestions on how to measure the amplitude of a wave with only one anti node which is beimg electromagnetically damped.

ALi-B

iTrader: (1)

Electrical Strain gauge? Although I'd think the amount of deflection of a sheet of thin metal would probably be beyond its limits.

farmer1

Im not sure how one of them works, but shall have a read up.

Basically the sheet of metal will be set into continuous osillation and the device will continue to try and oscillate it whilst it is being damped by the electromagnet.

It is important that the measuring of amplitude does not affect the oscillations in anyway.