How does temperature affect current and resistance?

[ToddB64]

Greetings!

I found the following statements related to the title on the Internet and they seem to suggest that it would be beneficial to metal detect during cool or cold weather to gain improved flow of electrical current in metals, as the inverse result of lower ohms or resistance.
I've been involved in the hobby of metal detecting for over 16 years and this is my first time to come across information leading me to this conclusion. Since I haven't been a fan of cold temperatures in my latter years, I haven't done enough metal detecting in cold weather to gauge if there is in fact a positive improvement when the ground and any metal targets in the ground are cool or cold.

Your opinions on my conclusion and/or your personal experiences of metal detecting in cold vs the warm time of year would be appreciated.

How does temperature affect current and resistance?

Temperature affects how electricity flows through an electrical circuit by changing the speed at which the electrons travel. This is due to an increase in resistance of the circuit that results from an increase in temperature.

The effect of heat on the atomic structure of a material is to make the atoms vibrate, and the higher the temperature the more violently the atoms vibrate. The more the atoms jostle around in the material, the more collisions are caused and hence the greater the resistance to current flow.

For metals, the thermal conductivity is mainly a function of the motion of free electrons. As the temperature increases, the molecular vibrations increase (in turn decreasing the mean free path of molecules). So, they obstruct the flow of free electrons, thus reducing the conductivity.

Thanks,
ToddB64

 

[Odanscoils]

Found my best Palladium multi carott ring in the ice.
Though in electronics. Just a slight difference in ambient temperature's. Not much difference in ohm's resistance, conductivity.
A few hundred degrees below zero.
Makes a Big difference.
And glowing red iron is non magnetic
Surprised they don't mention conductive and inductive differences by temperature.
I've found the ground better more because of water saturation than anything else in winter.

 

[still looking 52]

I've found that the condition of the ground makes a difference in depth, moist ground equals deeper depth, dry ground equals shallower depth.
The hotter it is outside usually causes the ground to dry up causing less depth.
I don't think the actual temperature has much effect on depth.

 

[Picketwire]

If you have an ohm meter, you can test to see how much difference it makes. Check the resistance on a wire, then put it in the freezer check again, then heat it up and check it. Better yet, put a coil in the freezer and quickly do an air test after you take it out. Let it warm to room temp and check again. The engine control module in your automobile has lots of electronics and works in both hot and cold weather. Again, an air test, would indicate if there is a distinct loss of depth, that is, if you can keep EMI at the same level at your test site. Also, cold weather lowers battery voltage which could negate any gains.

 

[ToddB64]

Found my best Palladium multi carott ring in the ice.
Though in electronics. Just a slight difference in ambient temperature's. Not much difference in ohm's resistance, conductivity.
A few hundred degrees below zero.
Makes a Big difference.
And glowing red iron is non magnetic
Surprised they don't mention conductive and inductive differences by temperature.
I've found the ground better more because of water saturation than anything else in winter.

Thanks for posting Odanscoils !

Re your last comment, that's been my experience too.

ToddB64

 

[ToddB64]

I've found that the condition of the ground makes a difference in depth, moist ground equals deeper depth, dry ground equals shallower depth.
The hotter it is outside usually causes the ground to dry up causing less depth.
I don't think the actual temperature has much effect on depth.

Hi still looking 52

Thanks for posting ! My experience agrees with what you said.

ToddB64

 

[ToddB64]

If you have an ohm meter, you can test to see how much difference it makes. Check the resistance on a wire, then put it in the freezer check again, then heat it up and check it. Better yet, put a coil in the freezer and quickly do an air test after you take it out. Let it warm to room temp and check again. The engine control module in your automobile has lots of electronics and works in both hot and cold weather. Again, an air test, would indicate if there is a distinct loss of depth, that is, if you can keep EMI at the same level at your test site. Also, cold weather lowers battery voltage which could negate any gains.

Hi Picketwire !

Interesting ! Yes, I do have a Volt/Ohm meter, so might try the first test you suggested using a wire, etc., etc..

Thanks for all of the information.

ToddB64

 

[Odanscoils]

I've found that the condition of the ground makes a difference in depth, moist ground equals deeper depth, dry ground equals shallower depth.
The hotter it is outside usually causes the ground to dry up causing less depth.
I don't think the actual temperature has much effect on depth.

Not in metal detecting.
Moisture is the major factor.

 

[Odanscoils]

Hi Picketwire !

Interesting ! Yes, I do have a Volt/Ohm meter, so might try the first test you suggested using a wire, etc., etc..

Thanks for all of the information.

ToddB64

I have a couple Megers and a ground resistance meter for setting up grounding on radio towers.
Capable of seeing the difference in wires just a few inches difference.
A mile or six inches. Doesn't matter.
The Megers we used to use to measure to the Fault in underground highvoltage Powers line.
Now we use a very high dollar Fault Wizard.
It will also Thump the primary at the fault.
You can actually feel the ground Thump when your near it. Very dangerous piece of equipment.
Love old school analog equipment.
Right place right time every now and then.
Everything tested an calibrated before mothballing.

If someone wants to help set up a test.
I'm all set. Though I need Help. Disabled.
Some pics of a few pieces of a scrapped Beta Lab.
Love my company.

 

[Odanscoils]

If you have an ohm meter, you can test to see how much difference it makes. Check the resistance on a wire, then put it in the freezer check again, then heat it up and check it. Better yet, put a coil in the freezer and quickly do an air test after you take it out. Let it warm to room temp and check again. The engine control module in your automobile has lots of electronics and works in both hot and cold weather. Again, an air test, would indicate if there is a distinct loss of depth, that is, if you can keep EMI at the same level at your test site. Also, cold weather lowers battery voltage which could negate any gains.

With a Good ohm meter.
Capable of mega ohms.
Place two screwdrivers 12 feet apart.
Try wet season and dry season.
Same location.
Record the different readings each month.
Great indicator of best times to hit the ground Hard. Looking for Old Deep missed targets.
If I remember correctly.
Theirs also a technique using a car battery to overcharge the ground to get the Deepest Out of reach targets.
Remember getting worms outta ground. 1950-80's.
Two screwdrivers and an extension cord.
10' apart.
They'd come wriggling outta the ground.
I still remember the kits they used to sell.
Though ground current potential shut that down.
Just the difference between your feet walking.
Causes enough voltage potential on bare feet doing worming to kill. Yes it happened.
Near a downed burning high voltage line.
NEVER WALK.
Seriously
Bunny Hop !!!
It's the step potential like a bullseye from center of target. It's where the primary high voltage line is down. Each bullseye ring can be thousands of volts difference between your feet walking.
30' ft away your usually ok unless it's a puddle.
Bunny Hop
Save yours or a loved ones life.
Absolutely No Joke.
Look it up.
It's my Job.
To make you safe and comfy at home !!!

 

[u2robert]

I don't know about cold temperatures if it gets below 80 degrees here in FLA, I'm cold
But I do know wet ground will give you better depth some say 30 % deeper depth.
I don't know if it's that deep, but it is deeper for sure.

 

[Nauti]

Nautilus thought it mattered as you had to balance the coil for best results and it was recommended to rebalance if the temprature changed.