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Gajan1234
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How does the current is reduced by the resistance. How is the rate of charge flow decrease in the whole circuit if the variable resistor is placed in the middle of the circuit?
Gajan1234 said:How is the rate of charge flow decrease in the whole circuit if the variable resistor is placed in the middle of the circuit?
It is very hard to explain my confusion. What I mean is how will the current know to change its rate if the the variable resistor attached in the middle of the circuit. Does this mean tha the current is different before and the variable resistor. If it is then it contradict the fact that current is same in a series circuit.anorlunda said:Resistance is defined as the ratio of voltage to current.
That depends on the circuit.If you want better answers, you must learn to ask more specific questions.
This is a good reply. Thanks for the help.ProfuselyQuarky said:Yeah, a resistor is actually a pretty boring component when it comes to electricity. It doesn’t really do anything actively, which makes its function difficult to understand. Actually, a lot of resistors are nothing more but a piece of bent metal wire. Resistors ultimately just allow you to acquire the proper voltage and current that you want in you circuit. If you have, say, a 9 volt battery, a resistor can decrease the voltage to 6 volts or 4 volts, for example.
It gives you control and power! Mwahahaha
anorlunda said:No, you need a picture to show the circuit.
But things in series do have the same current. If you have an idea that contradicts that, the idea must be wrong.
The only difference between a normal resistor and a variable resistor is that the variable resistor allows you to adjust the resistance between specific points within the circuit. With a normal resistor, you would have to add two or more resistors to acquire the voltage you want. A variable resistor does it all for you.Gajan1234 said:But will the current be different if it has gone through the variable resistor.
Gajan1234 said:Will the current reading on A1 be different to A2, the function of the resistor is to decrease the current so for this to happen, doesn't the current need to flow through the resistor?
Gajan1234 said:Will the current reading on A1 be different to A2, the function of the resistor is to decrease the current so for this to happen, doesn't the current need to flow through the resistor?
Thanks indeed for your helpsophiecentaur said:I absolutely hate water analogies but here is a good one to illustrate the 'startup thing'.
You have a set of reservoirs at different levels on a hill. They are all empty except the top one, which is kept full (your battery). They are connected in series by a set of pipes and they have water turbines which drive machinery at their inlets (the resistances in series). When you connect the top reservoir, water starts of flow and starts to fill the second reservoir, which soon starts to overflow into the third (but starting with only a trickle, of course). After an interval, the reservoirs are more of less full and water starts to flow out of the bottom reservoir - a trickle and then full on. Only when this whole process has completed can you consider it a steady state and the turbines will then all 'know' how much power to transfer to the machines. Tens of minutes instead of less than 1ns but the principle is the same. At the end, you can say that the gravitational potential energy (your voltage) is shared out according to the drops in height between reservoirs and the water current is the same all the way down - but not before.
Any time - just put a cheque in the post. hahaGajan1234 said:Thanks indeed for your help
Uh, seriously?ProfuselyQuarky said:Actually, a lot of resistors are nothing more but a piece of bent metal wire.
I was just trying to dumb everything a bit down, phinds.phinds said:Uh, seriously?
I think you carried it way too farProfuselyQuarky said:I was just trying to dumb everything a bit down, phinds.
Okay, you're rightphinds said:I think you carried it way too far
ProfuselyQuarky said:Actually, a lot of resistors are nothing more but a piece of bent metal wire.
phinds said:Uh, seriously?
The converse is true at least.ProfuselyQuarky said:I was just trying to dumb everything a bit down, phinds.
That could be interpreted two ways...sophiecentaur said:Any time - just put a cheque in the post. haha
Mmm. I see what you mean. But the risk of an actual cheque arriving is pretty low. In that unlikely event, it would have to be diverted to PF funds.berkeman said:That could be interpreted two ways...
THANK YOU SIRjim hardy said:@Gajan1234
It may be helpful to oversimplify.
Have you had high school physics ? Remember atoms and electron shells ? spfd etc ?
It helps a beginner to imagine yourself very small and inside the wires.
Envision yourself in a lattice of metal atoms, each atom with its electron cloud the size of a basketball and a nucleus smaller than the ball of a ball point pen.
In fact, when just beginning you might find it worthwhile to imagine yourself a free charge hopping along from atom to atom along its outermost electrons..
In wires those hops are easy because most metal atoms don't hold tightly to charge in their outer electron shells.
Inside a resistor the atoms are not so friendly and it takes work to get from one to the next. That work shows up as heat. Resistance is in that sense analogous to friction.
Charge has to be pushed through resistive material and heat results. Rub your hands together and feel the heat of friction.
Back to our hopping charges...
Current flows in a closed loop.
By the time you have hopped around the whole loop you've made some easy hops and some difficult ones.
How hard were you pushed by the voltage?
How hard were you resisted by the resistor?
The guy behind you was pushed by same voltage, so was guy behind him...
the quicker your hops the more charges can move through in a given time.
Ratio of available voltage to resistance determines how many charges can push through every second
and charges per second is the definition of current.
Volts
__________ = current
resistance
that is Ohm's Law and it really is that simple.
Believe in algebra and make mental models for yourself.
Keep tweaking your models until they lead you intuitively to the formula. It beats memorization...
Imagination is your friend , provided you put it to work...
old jim
So many good answers...however, I like to add another one which is based on some fundamental electrical rules.Gajan1234 said:How does the current is reduced by the resistance. How is the rate of charge flow decrease in the whole circuit if the variable resistor is placed in the middle of the circuit?
LvW said:At first - the "current" is not "reduced" by a resistance - instead, it is determined by the driving voltage and the connected resistance (Ohm`s law).
But this is only the RESULT of some considerations and not yet an EXPLANATION.
When your logic leads to an impossible conclusion then one of two things is wrong:Ario Barzan said:If the current at both sides of the variable resistor is not the same, the difference must accumulate inside the resistor. Now, I ask you how is this possible?
Electric current is the flow of electric charge through a conductor. It is measured in amperes (A).
Resistance is a measure of how difficult it is for electric current to flow through a material. It is measured in ohms (Ω).
Resistance reduces the flow of electric current. The higher the resistance, the lower the electric current.
The factors that affect resistance include the material of the conductor, its length, its cross-sectional area, and its temperature.
Resistance can be reduced by using materials with lower resistance, shorter conductors, thicker conductors, and keeping the temperature of the conductor low.