| Electronics > Beginners |
| Using a small resistor in some water instead of a power resistor? |
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| MLXXXp:
--- Quote from: Zero999 on November 03, 2019, 06:47:34 pm ---I omitted the words "most of". I've edited my post. --- End quote --- And IMHO it's still wrong. Although it depends on what one defines the meaning of the word most to be in this case, personally, for two resistors of almost identical value in parallel, I wouldn't consider the small amount of additional current that the lower value one draws, compared to the higher one, to be most of the current. A clear statement for all cases would be to use more of, not most of: Yes, connecting resistors in parallel causes more of the current to go through the one with the least resistance. |
| alpher:
And I just did a quick and dirty test of your theories. Put a 10 \$\Omega\$ 1/4W resistor in a glass of tap water, run 1A through it (10V) for good 5 minutes, some bubbles and not much else. Same resistor burned in air in less than 10 second. So my conclusion, if you need some quick and dirty 10W capable resistor for a few minutes, go ahead and dump your run of the mill 1/4 watter in a glass of water. :) :) :) |
| Siwastaja:
--- Quote from: alpher on November 04, 2019, 05:14:40 pm ---And I just did a quick and dirty test of your theories. Put a 10 \$\Omega\$ 1/4W resistor in a glass of tap water, run 1A through it (10V) for good 5 minutes, some bubbles and not much else. Same resistor burned in air in less than 10 second. So my conclusion, if you need some quick and dirty 10W capable resistor for a few minutes, go ahead and dump your run of the mill 1/4 watter in a glass ow water. :) --- End quote --- Yes. Do note that the speed of the corrosion starts to accelerate. If the tap water is relatively low mineral, the rate of reaction is fairly low first, but the more it reacts, the more metals are dissolved into the water, making it more conductive, again making the reaction happen more quickly. An accelerating spiral of death. |
| Zero999:
--- Quote from: MLXXXp on November 04, 2019, 05:09:21 pm --- --- Quote from: Zero999 on November 03, 2019, 06:47:34 pm ---I omitted the words "most of". I've edited my post. --- End quote --- And IMHO it's still wrong. Although it depends on what one defines the meaning of the word most to be in this case, personally, for two resistors of almost identical value in parallel, I wouldn't consider the small amount of additional current that the lower value one draws, compared to the higher one, to be most of the current. A clear statement for all cases would be to use more of, not most of: Yes, connecting resistors in parallel causes more of the current to go through the one with the least resistance. --- End quote --- This is why one should learn the basic maths behind it, to avoid getting into semantics. |
| AVGresponding:
--- Quote from: Siwastaja on November 04, 2019, 05:17:34 pm --- --- Quote from: alpher on November 04, 2019, 05:14:40 pm ---And I just did a quick and dirty test of your theories. Put a 10 \$\Omega\$ 1/4W resistor in a glass of tap water, run 1A through it (10V) for good 5 minutes, some bubbles and not much else. Same resistor burned in air in less than 10 second. So my conclusion, if you need some quick and dirty 10W capable resistor for a few minutes, go ahead and dump your run of the mill 1/4 watter in a glass ow water. :) --- End quote --- And also do remember NOT to drink the water afterwards... :-DD Yes. Do note that the speed of the corrosion starts to accelerate. If the tap water is relatively low mineral, the rate of reaction is fairly low first, but the more it reacts, the more metals are dissolved into the water, making it more conductive, again making the reaction happen more quickly. An accelerating spiral of death. --- End quote --- |
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