- Joined Jan 6, 2007
i know this sounds like a dumb question, but does voltage increase if resistance increases? & why?(as opposed to current decreasing from resistance).
Correct. Once you grasp this fundamental concept you can extrapolate the workings of Ohm's Law to any problem.Oh ok i get it, so if we are keeping one value(1) constant and we change another value(2), than in order for the value(1) to stay constant, than we must change value(3) to oppose value(2).
You are asking one of the fundamental questions of physics. The electric charge is a fundamental property of atoms which determines the electromagnetic interactions experienced by atoms - accept this as a given. You are aware that the atom is comprised of Protons, Neutrons and Electrons. From the perspective of electric charge, protons have a net positive charge, electrons have a net negative charge and neutrons have net neutral charge. You should also be aware that like charges repel and unlike charges attract.but what is a charge, and how does it change every second?
Correct.Actually this helped tremendously, thanks. So practically, i see how current is the flow and result of the applied voltage(no V=no I).right?
Correct.so should less voltage equal less current keeping resistance constant?
For the purposes of resistance, yes. The current-voltage relationship is slightly more complicated for inductors and capacitors, but do not concern yourself with this here.That being said, and current being a cause of voltage, than current is an exact variation on voltage right?
The shunt resistor is placed in series with the circuit which you are measuring the current through. The current flowing through the shunt resistor will cause a voltage drop across the resistor which you measure with the voltmeter. By using Ohm's Law: I = V/R (Current = Voltage drop across shunt resistor/Resistance of shunt resistor), you can derive the current flowing through the circuit.Another thing im having trouble with is using a shunt resister across a voltmeter to mesure current.(i dont get it!)
That is a good point. As a continuum from my previous post, it is correct to say that the shunt resistor will have an influence on the measurement for the quoted reason. Ideally, when you place your shunt/meter in series with the circuit you would like it to present a zero resistance (which is impossible for all practical purposes) in order for it to have no influence on the measurement. In the same way when you measure voltage you place your meter in parallel around the component(s) you measuring the voltage of, then you ideally want the meter to present an infinite resistance thus to prevent it drawing current and thus again influencing the measurement.You should always remember you can ONLY measure current in SERIES things go bad when you measure current in parallel. If you shunt a resistor in to measure current it is like throwing it into parallel so that means you might not be getting the correct value of current because your measuring the current that the resistor draws and not what the circuit is drawing.
Ok, lets deal with one method at a time: The Branch Current Method. Where exactly in the AAC tutorial are beginning to not understand it? What is posing you the problem?Thanks i get what all you guys are talking about, i read about it a week
ago. I now have another problem in electronics (as far as learning goes)
Im currently reading chapter 10 on DC network analysis of volume 1 DC,
and im having trouble with the branch current and mesh current method
(espesialy branch method).
Branch Current Method
Mesh Current Method
I get most of it, but my only problem is at the the end when it comes time to figure out the equations to come up
with the amount of current through the individual resistors(i dont know how to solve these particular equations!).
As it happens what you are saying is also correct, although using a shunt in the way I have previously described is also accurate. The situation you have described refers the shunt resistor placed in parallel with the coil in a Perminent Magnet Moving Coil (PMMC) ammeter. The PMMC meter experiences a full-scale deflection, and the shunt resistor connected in parallel is designed to increase its current measurement range (as you have described). The shunt resistance in this case is configured to ensure only a fraction of the current bypasses the coil and hence the full-scale deflection of the whole measurement system comprising the shunt resistor and PMMC meter is given by:Howdy, it's actually a shunt resistor connected across an ammeter or milliammeter to reduce the current through the meter thus increasing its range. It's been 30 years since I've studied instrumentation so I'm no expert here but if you have a 5 amp meter and place a shunt with 1/10 the resistance of the meter across it then it will take 50 amperes flowing through the meter and shunt for the meter to read full scale instead of 5 amps. Many times the current ratio is printed or stamped on larger shunts.
Here lies my troubles with branch current method:Ok, lets deal with one method at a time: The Branch Current Method. Where exactly in the AAC tutorial are beginning to not understand it? What is posing you the problem?
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by Luke James