Ohm's Law and Kirchoff's two laws will get you a long way in circuit design. Without them you will not get started. Only two options:
1. learn how to use them
2. find another hobby (or stick to building well-designed kits which need no debugging)
1. learn how to use them
2. find another hobby (or stick to building well-designed kits which need no debugging)
Several people pointed out that if you know a resistor value, which you do, and measure the voltage across the resistor, which you did, then the current trough the resistor is voltage divided by the resistance. You said you could do division.
So what's 'I don't understand'?
Jan
The idea is to keep the thread running as long as possible. 🙄
Don´t expect "logic" in it.
all I needed was someone to tell me that.
of how to convert the voltage across the resistor and the resistance of the resistor to convert to current.
but no one was giving me a straight answer and i couldn't figure it out on google.
I thought I had to do it based on the voltage across the resistor. and based on the output and input voltages divided added or subtracted in some way
rather than the resistance of the resistor
is there a way to do it without knowing the resistance of the resistor? then being able to figure out current as well?
of how to convert the voltage across the resistor and the resistance of the resistor to convert to current.
but no one was giving me a straight answer and i couldn't figure it out on google.
I thought I had to do it based on the voltage across the resistor. and based on the output and input voltages divided added or subtracted in some way
rather than the resistance of the resistor
is there a way to do it without knowing the resistance of the resistor? then being able to figure out current as well?
There are the three terms, voltage, current, and resistance. You need to know two of them to calculate the third.
To calculate power, you also need to know two of them.
To calculate power, you also need to know two of them.
If you have another R of which you DO know the resistance, you can put it in series with the unknown resistor. Then measure the voltage across the known resistor, use that to calculate the current I, and that is also the I through the unknown R because they are in series.
The nice thing is, now that you know the I through the unknown R, you can measure the V across the unknown and presto! you can calculate the value of the unknown R!
R = V/I.
Jan
If you know the voltage across the resistor then you use Ohm's Law.realflow100 said:
If you don't know the voltage across the resistor directly then you use Kirchoff's voltage law to calculate it from voltages you do know.
If you don't know enough voltages but have enough other information then you might be able to do it using algebra or formulas derived from algebra.
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