Need help determining Proper Current and Resistance Values

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Elektrotechnik

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Hello,

I'm trying to verify that my math is correct for a reliability test that I'm designing. I'm using 2W load resistors that are powered by 14 Volts. Am I correct in needing these 2W load resistors to be rated at 10 miliOhm? Each resistor would be receiving 143 mA, and I used that to determine the 10 miliOhm resistance.

I have 9 of these load resistors. In the test, they are powered by a voltage-driven power source of 14 V. They are connected in parallel with the 14 V and the ground.

How much current do I need to supply from the power supply?
 
130723-1729 EDT

Your question is not clear.

As an EE you should be able to determine the resistance at a given voltage to dissipate a specified amount of power.

Are you testing resistors or something else?
What do you want to determine with the test of whatever it is that you are testing ?

.
 
I'm confused. What are you trying to calculate? It sounds like you have a 14V (DC?) power supply, and you plan to connect 9 resistors in parallel across the output terminals of the power supply. Now here's where I get lost.

Do you have 10 milliohm resistors on hand, and you're trying to calculate the current through each one? Are you trying to find what size resistor you should use in order to have 143 mA flowing through each of the 9 resistors? Are you trying to find what size resistor you should use in order to dissipate 2W in each of the 9 resistors? Please clarify what you're looking for, and it will be easier to help you out.
 
Sorry for the confusion. It was the end of the work day?

But I?m running humidity tests for the hookup wire that I?m using. I?ve got 9 loads connected in parallel that I want to dissipate 2 Watts, from a 14 V Power Supply. I chose each load to have 100 Ohm resistance. And therefore, I need (0.14A * 9) = 1.26 A from the power supply.

Is my math correct?
 
Your math is fine, and so is your approach. I will take the class through the exercise. ;)

Starting with a 14 volt source and a desire to dissipate 2 watts, and using W = V*V/R, I calculate the resistance to be 98 ohms. You selected a 100 ohm resistor, instead of a 98 ohm resistor, quite likely because nobody makes a 98 ohm resistor.

Next, using I = V/R, 14 volts divided by the 100 ohms that you selected would give you 140 mA. Finally, nine of those would give you a total of 1.26 amps.
 
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