# Do 40 Watt 1 Ohm resistors exist

1. Mar 5, 2016

### houlahound

My local hobby store says no.

I want to draw a full 40 Amps from my power supply to play with a few formulas that give the magnetic field strength as a function of distance and current from a wire. The wire will be car battery cables. I have a calibrated Gauss meter for field measurements.

Would this set up work, what catalogues have a 40 Watt 1 Ohm resistor?

2. Mar 5, 2016

### Nidum

Last edited by a moderator: May 7, 2017
3. Mar 5, 2016

### 256bits

Your volts, amps, watts do not make sense.
I could be missing something ...
40 watts through a 1 Ohm resister - that 6.3 volts and 6.3 amps.
40 amps through a 1 Ohm resistor - requires an emf of 40 v, thus your resistor needs to be 1600 watts.

4. Mar 5, 2016

5. Mar 5, 2016

### houlahound

Holy crap that's the resistor from hell.
Didn't think the numbers through before i posted.
My power supply, switched mode, is rated at 40 Amps. It is a variable voltage to 12 volts. I use it for my radio but never measured what current it draws. My licence has limited watts for transmission. Don't know what antenna power equates to 40 Amps from the power supply.

6. Mar 5, 2016

That is a 2000W answer to a 40W question - in short yes, they exist... there are a few ways to do this. But car headlamps are a good - low cost solution. Ray Bans anyone?

7. Mar 5, 2016

8. Mar 5, 2016

### houlahound

I got some carbon rods about half inch diameter from an old time movie projector, will put them in sliding contact to make a variable resistance...what could go wrong?

9. Mar 5, 2016

### jim hardy

10. Mar 5, 2016

### houlahound

Cool link, I wanted to build a lighting museum at one point, still might.

I am prolly the only living guy that lived in a time and place that carbide lights were the only source of lighting.

The good thing was we could take them to fishing holes and blow them up and get a feed of fresh fish, try doing that with yr fancy schmancy LED's.

11. Mar 5, 2016

### meBigGuy

LOL --- you gonna read, or you gonna fish?

12. Mar 5, 2016

### jim hardy

i thought i was the only one here that old.

Used to do spelunking in Missouri.

13. Mar 5, 2016

### houlahound

Ha, ever use a party line ie a piece of fencing wire strung between trees for miles. A dynamo powered phone with a lead attached to the line by swinging a rock tied to one end to wrap around the party line. Lightning would blow your ears out or worse.

Everyone could listen to your conversations, and everyone could talk at the same time. Might have been why multiplexing and frequency division on a single optical fibre was born.

I still have a dynamo, use it to show kids induction, gives a hell of a boot.

If anyone would have tried to say one day we will have an internet they would have been burned at the stake for witchcraft.

Last edited: Mar 5, 2016
14. Mar 8, 2016

### Jeff Rosenbury

That resistor is wire wound, so may or may not be suitable for RF work.