Today we will see Ohm's Law definition in the electricalcircuit. So Ohm's law is very simple algebraic relationship between thevoltage, current and the resistor in the circuit. So, let us say we have onevoltage source which is connected to a one resistor R.So, because of that thecurrent will flow through this resistor R.
State Ohm's Law
So, according to the Ohm's law atconstant temperature the electrical current flowing through a fixed linearresistor is directly proportional to the voltage applied across it and it isinversely proportional to the resistance. So, the current which is flowing throughthis resistor R is directly proportional to the voltage applied across it and itis inversely proportional to the resistance of this resistor. So, now let'sunderstand this Ohm's law by taking a water tank analogy. So, let's say we haveone water tank and at the bottom of the tank we have connected one hose pipe. Soin this analogy the water in the water tank can be represented as a charge inthe electrical circuits.
While the level of the water in the tank or a waterpressure represents the voltage in the electrical circuit. The diameter of thishose pipe represents the resistance in the circuit and the flow of waterthrough this hose pipe represents the current in the electrical circuit. So, nowlet's take up one example. Here, we have a two water tanks which contains an equalamount of water in the both the tanks. But the both the tanks have a differentdiameter of hose pipe. So, definitely the tank which has a larger diameter hosepipe will have a more flow of water.
In the second case,where the diameter of the hose pipe is small, the flow of water will be less.Because the water will observe more amount of resistance through this lowerdiameter hose pipe. While when it flows through a larger diameter hose pipe, itfeels less amount of resistance. So let's correlate it with the electrical circuit.Let us say that we have a two electrical circuit which has a same voltage sourcesbut the value of resistance in the both the circuit is different.
In one case onecase it is R1 and in second because it is R2. And So according to the Ohm's law,the current flowing in the first circuit can be given as V devide by R1. In the secondcircuit, it can be given as I 2 is equal to V devide by R2. Now here, the resistance R2is less than R 1, so the more current will flow through this second circuit asthe value of resistance is less. But in the first circuit, as the value ofresistance R1 is more, So less amount of current will flow. So for both thecircuits I 2 will be greater than I1. Now let us take second example inwhich we have a two water tanks with the same diameter of hose pipe but in theboth the tanks the amount of water level is different.
In the first tank we have aless amount of water, so because of that pressure exerted at the bottom of thishose pipe will be less. So because of the less pressure, the flow of water will beless.while in the second case, as it contains more amount of water thepressure exerted at the bottom of the hose pipe will be more. Because of themore pressure the flow of water will be more through this pipe. So now let uscorrelate it with the electrical circuit. So, let us say we have our two electricalcircuits with a different voltage sources.
But both the circuit contains asame amount of resistance, that is R. So, the current flowing through the FirstCircuit I1 can be given as V 1 devide by R. While in the Second Circuit, it canbe even by I2 is equal to V2 /R. Now here the voltage source V 2 isgreater than V 1, so the more amount of current will flow through the secondcircuit. So we can say that for both the circuits if V2 is greater than V 1 thenI 2 will be greater than I1. So through this both both the examples, wehave seen that if we keep one parameter constant.
Let's say if we keep voltageconstant and we change the value of resistance, or if we increase the valueof resistor R then the current will reduce in the circuit, or if we keep theresistance R constant and if we increase or decrease the value ofvoltage in the circuit and accordingly the current will increase or decreaseproportionally. So, now let's take a examples based on the Ohm's law. In thefirst circuit we have a one voltage source with a 5 volt which is connectedto a 10 ohm resistor. So we need to find what is the current that is flowingthrough this 10 ohm resistor.
So the current I can be given as V divide by R. so here the voltage is 5 volt and the resistance is a 10 ohm. So thecurrent flowing through this circuit can be given as a 0.5 ampere, now in thesecond circuit if you see we have one 5 volt voltage source which is connectedto a unknown resistor R. And the current that is flowing through thiscircuit is given as a 2 ampere. So we need to find , what is the value ofthis resistance R. So we know that according to the Ohm's law, I is equal toV divide by R.So we can write R is equal to V divide by R. Now here we know thevoltage that is a 5 volt,and the current that is flowing through that circuit isa 2 ampere.
From this the value of unknown the resistance will be the 2.5ohm. so basically this Ohm's law is a relationship between the voltage, currentand resistor. so if you know any of the two quantities you can find the thirdone.So let's say you know the current and the resistance in the circuit thenvoltage can be defined as V is equal to I*R. Or if we know the voltage andcurrent in the circuit then the resistance R can be given as V divide by I that is Vdivide by i .Likewise, current I can be given as V divide by R. so in the Ohm's law if weknow any of the two quantities we can find the third one. now so in the lastvideo we had seen, what is power in the electrical circuits.
Ohm's Law Formula
And it is given byrelationship P is equal to V *I .so according to the Ohm's law we know thatthe current I can be given as V divide by R Now let's put this into this equation sowe'll get V*(V/R),that is a V^2/R. so power can also bedefined by V^2/R. now we know that what voltage can also be written asI *R, according to the Ohm's law.So this power P that is V into I can alsobe written as(I*R)*I, that is a I^2*R. so power can bedefined as either product of voltage into currentor V^2/R or I^2*R. so in this way we get a relationshipbetween the power, voltage, current and the resistance in the circuit. So let'ssee this pie chart which shows all the possible relationship between thevoltage, current, power and resistor.
So here if we know any of the twoparameters in the circuit let's say if we know current and power in the circuitthen we can find the remaining two parameters in the circuit . so if you knowcurrent and power when the voltage can be defined as a P divide by I. Likewise, theresistance R can be defined as a P divide by I square. so in this way if weknow any of the two parameters, we can find the remaining two . so let's say ifwe know power and resistor in the circuit then we can find the current bysquare root P divide by R and the voltage that is given by square root P into R.so in this way if you know any of the two quantities we can find the other two.so let's take a example based on this relationship.
We have one 10 volt voltagesource which is connected to a unknown resistor R .And the current is given thatthat which is flowing through the circuit is a 2 ampere . So, we need to findthe value of this resistor and the power dissipated across this resistor. so firstof all, let's find the value of this resistance. so according to the Ohm's lawR is given by V /I .so here voltage is given that is 10 V and the currentthat is flowing to the circuit is a 2 A. so from that we find that the value ofresistance R is a 5 ohm.
Ohm Calculator
Now the power P we had seen that it can be definedas V*I. So, here we know the voltage is a 10 volt and the current is a 2ampere. The power that is dissipated across the resistor will be 20 W. Nowlet us take one more example, here we have a unknown voltage source V which isconnected to a 10 ohm resistor. And the current flowing through the circuit isgiven, I is equal to 1 A . So, we need to find the voltage, this unknown voltageand the power dissipated across this 10 ohm resistor. So, first of all, let's findthe voltage V which is given by I * R. So, here we know the I is 1 ampere andthe value of resistor R is a 10 ohm.
So the voltage in the circuit will be the10 volt. And the unknown voltage source has a voltage of 10 volt. Now the power P canbe given by I^2*R, that we already have seen. So here current is 1ampere that is a 1 square into, R that is a 10 ohm so we get a 10 W. So, thepower dissipated across the resistor will be 10 W. So, using this Ohm'slaw we can find the voltage, power current and resistor in an electricalcircuit, if we know any of the two parameters in the electrical circuit. SoI hope you understood what is Ohm's Law in the electrical circuit and usingthis how you can find the four different parameters in the electricalcircuit.
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