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# voltage and current source

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#### preethi19

##### Full Member level 5
Hi all i know this is a very basic question but i was just little curious abt this. Suppose say a current source connected by a wire (and nothing else no resistor) then the current flows through the circuit. What will the voltage be as there is no resistance der (assuming the wire resistance is zero resistance)? Because then I=V/R. So I=V/0... so will the current equal infinity??? but we have given a specific current source which is fixed so how can it go to infinity and what will be the voltage?? Because current can't flow without any force pushing it. So if current does flow so some amount of voltage must exist right? Or is it that the current source provides the force required to move the charge through the wire???

Second is when we connect current source by a wire current flows. but say we connect a voltage source through a wire (again assuming wire has zero resistance) will current flow through the circuit. Because if a voltage exists then there is a force that pushes the charged particles through the wire right from higher to lower potential. Becoz i always took voltage as example as water flow. Say water doesnt flow when the level between two points are the same. Say you lift up one point (causing potential difference) then water flows down. So isnt voltage enough for current to flow through the circuit. Why is resistor always added??? Because say 5 volt is connected by a wire. One point will have positive charges and other side will have equal amount of negative charges. so one terminal say positive charge will attract with great force the negatively charged terminal. so with no resistance or anything voltage exists and so charges move around the wire due to the force given by the voltage and voltage also exists. V=IR. say R is zero then V= I*0 and then voltage is zero. But say i am clearly connecting a 5 voltage source so how can voltage go to zero then...I am little confused. Can someone please explain

Finally what is the difference between voltage and current source. Both are making current flow through the circuit. Even a current source has one terminal of positive charges which is attracted to the negative terminal of the current source.
Thank you!!!

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We all know current will not flow until unless the path doesn't get complete. In your case when you pass the current in the zero resistance wire. The data which we will be reading at the other end of the resistor will be voltage. So this scenario only works for finding the unknown resistance value. If you are not reading or connecting the zero resistance wire. Then nothing flows through that. Because the circuit doesn't gets complete.

In your sceond case, It is almost something like you are shorting the two terminals of the voltage source. You will knowing the scenarion what happens if we short two terminals of voltage source.....

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Finally what is the difference between voltage and current source. Both are making current flow through the circuit.
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In simple terms,

in a voltage source,
-- its magnitude is constant.
--the magnitude of the current flow is determined by the components values connected in the circuit.

in a current source,
-- its value is constant.
--the magnitude of the voltage of the circuit is determined by the components values connected in the circuit.

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