# AC signals in water

Discussion in 'General Electronics Chat' started by lionking, Jun 1, 2005.

1. ### lionking Thread Starter New Member

Jun 1, 2005
1
0
Would an AC signal in water be the same as a signal in a wire?

2. ### thingmaker3 Retired Moderator

May 16, 2005
5,072
6
Water has more resistance than wire.

3. ### beenthere Retired Moderator

Apr 20, 2004
15,815
282
Hi,

It's kind of hard to tell what you are asking - AC signals is hard to interpret.

In general, though, copper wire is a conductor, and transmits electricity with very little loss and with predictable characteristics.

Water is an insulator. If it is pure, it does not conduct electricity. Water in a pond is full of electrolytes. If you place a voltage difference across a section of the pond, electrons from the negative wire can hitch a ride on an ion and travel to the positive wire. With AC, the potential reverses periodically, but the current just changes direction. The ampunt of electrolyte in the water can be measured by a conductivity meter.

4. ### legac Well-Known Member

May 4, 2005
54
0
Hi
would you mean underwater telecommunication?
I have learned that electromagnetic waves can be transferred underwater with very low frequency and it needs a very big frame of " antenna" to capture. I am not sure whether it is right or wrong.
Cheers
Legac

5. ### Erin G. Senior Member

Mar 3, 2005
167
1
RF (radio frequency) can (and does) travel through water at a "very low frequency". The Navy uses VLF to communicate with submarines, but it's not very effecient. The messages sent to subs via VLF are usually "Come to periscope depth to receive a message".

I don't know why anyone would have a reason to send AC through water at any frequency, though beenthere's explanation about how the current would act in water is correct.

6. ### _Raven_ Member

Jun 3, 2005
10
0

The answer is it depends on what characteristics of signal you want to compare. If you refer to frequency, yes they are the same. If amplitude, no. It really depends on the conductivity of the H2O, pure H2O is not a good conductor, but adding a small amount of impurities like NaCl will make it more conductive.

FYI....

Low frequency RF can travel in water and covers more area than travelling in air.
High frequency RF specially Microwave are more likely attenuated in H2O due to the fact that high frequency Electromagnetic energy were asorb by H2O.