Complicated Circuit
If the voltage of the source is 5
V
and the resistances are given by
R
1
=
2
Ω
,
R
2
=
7
Ω
,
R
6
=
∞
,
R
4
=
4
Ω
,
R
7
=
R
5
,
R
3
=
0
Ω
, and
R
7
=
∞
, then which of the following answers is true?
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6 solutions
How R7=R5 then R5= 3 and R7=infinity. Moreover, if there is no current through R1 then the voltage across R1 is zero.
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its an open circuit consisting 5v source and R1 resistor . if we apply kvl -5+Vr1=0 . hence Vr1=5v
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when you apply kvl on loop Vsource , R1 and R6 you did not include the voltage across R6, since the circuit is open voltage across R6 equals the supply voltage of 5V, hence kvl on that loop would be -5 +Vr1 +Vr6=0, so Vr1=5- Vr6 so that Vr1=0.
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@Diogenes Lador – yeah i'm sorry .i'm mistaken Vr1 should be zero and open ckt voltage will be 5v
we need closed loop to consider KVL
but there is an voltage source........if there is no current through a resistor,it doesn't mean that it will have zero voltage across it...
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its sure , if there is no current flowing, there is no voltage
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@Jineesh Tirur – if there is no current in the circuit it could be possible that voltage is exist in the circuit as we measure voltage across open circuit by Digital multi meter.
1-as current is not flowing through R7 it means this is an open circuit and in open circuit resistance doesn't matter on thatcircuit because no current flow and whatever we say R5=3 or R5=8 because the final resistance (R7) is at infinity.
2_resistance R1 is at 5v because current want path to flow it but voltage wants two terminal across it.and do not use ohm law there because ohm law is not applicable for open circuit.
since R5=R7, so how R7=infinity and R5=3??????
In the problem, we will have an open circuit, so we will have no current flowing Ohm's Law states that Voltage is equal to the product of Current and the Resistance V=I R. In finding the voltage of R1 we will get V = I R = (0 Ampere)*(2 ohms) = 0 volts
so the voltage across R1 is 0 volts so the answer is incorrect.
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ohm's law is not applicable for open circuit. So we cannot apply V=IR.we can measure voltage R1 just like a voltmeter whether we can measure voltage across R1 or Battery.the result is same.because no power dissipation for open circuit.
it's an open circuit, so no current flow, and therefore no voltage across R1.
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i agree with you
Hell0 Sir! if we connect the voltmeter across R1 then it show the voltage equal to battery.Why? because ohm law is not applicable for open circuit.current wants closed path but voltage wants two terminals.any queries then i can explain with some reason
since R5=R7, so how R7=infinity and R5=3??????
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Hello Sir as current is not flowing through R7 it means this is an open circuit and in open circuit resistance doesn't matter on thatcircuit because no current flow and whatever we say R5=3 or R5=8 because the final resistance (R7) is at infinity.
It is a wrong question... How R7=R5 then R5=3 and R7= infinity ?? heno
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1-as current is not flowing through R7 it means this is an open circuit and in open circuit the resistance doesn't matter on the circuit because no current flow and whatever we say R5=3 or R5=8 because the final resistance (R7) is at infinity.
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but why the hell do you write wrong questions,shame.
the voltage and current of R1 is zero
nice
pardon me but if the circuit is open the voltage across the 2 ohm resistor will never be 5 volts it will be zero. its indeed a complicated circuit when you say R5=R7 and you also give R5=3ohms and R7=infinity.
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i agree with you...i think that the problem is incorrect
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as current is not flowing through R7 it means this is an open circuit and in open circuit resistance doesn't matter on thatcircuit because no current flow and whatever we say R5=3 or R5=8 because the final resistance (R7) is at infinity.
Hello Sir 1-if we connect the voltmeter across R1 then it show the voltage equal to battery.Why? because ohm law is not applicable for open circuit.current wants closed path but voltage wants two terminals 2-as current is not flowing through R7 it means this is an open circuit and in open circuit resistance doesn't matter on thatcircuit because no current flow and whatever we say R5=3 or R5=8 because the final resistance (R7) is at infinity.
as the circuit is open so the voltage drop across R1 will be 0volts, this is what i think. so, the above mentioned answer is wrong.
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Hello Sir if we connect the voltmeter across R1 then it show the voltage equal to battery.Why? because ohm law is not applicable for open circuit.current wants closed path but voltage wants two terminals
open circuit voltage across r1 0 v
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if we connect the voltmeter across R1 then it show the voltage equal to battery.Why? because ohm law is not applicable for open circuit.current wants closed path but voltage wants two terminals
Voltage across 2ohm will be 0V as no current flows across it which means no voltage drop across it.
In this case the circuit is incomplete so all given options are wrong .. because the net current=0, .. there will be zero current in 2 ohm so there is no voltage drop V=0 . on logical basics we can say the maximum power loss will occurs in Open circuit by P= i^2R as R--->infinite .
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as current is zero so P=VI which is equal to zero.So power dissipation in an open circuit is zero if we connect the voltmeter across R1 then it show the voltage equal to battery.Why? because ohm law is not applicable for open circuit.Current wants closed path but voltage wants two terminals
zero voltage across 2 ohm resistor because all the voltages will drop in the infinite open circuit resistance
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power dissipation in open circuit is zero therefore voltage will not drop across the resistorR1
Pls, no voltage across R1, it is an open circuit...
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Hell0 Sir! if we connect the voltmeter across R1 then it show the voltage equal to battery.Why? because ohm law is not applicable for open circuit.current wants closed path but voltage wants two terminals
Of course there is voltage in R1. There's no current 'cause it's an open circuit, but voltage is just the tension present there. If you measure, you'll see that even in an open circuit there are voltage in the resistors, but no current flowing.
if current is zero that doesnt mean voltage across it is zero so the correct one is voltage across r1 is 5v
It is a wrong question... How R7=R5 then R5=3 and R7= infinity ??
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Hello Sir as current is not flowing through R7 it means this is an open circuit and in open circuit resistance doesn't matter on thatcircuit because no current flow and whatever we say R5=3 or R5=8 because the final resistance (R7) is at infinity.
The voltage across the R1=5v,because when current passes through the R1 after that it finds shortest path and flow towards the Battery,allows current follow shortest path.
I think the main problem here is the inconsistency of the given.
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Every thing in the question is right just watch it again.
voltage=0
vr1=0......
Voltage across Resistance R6 is 5V
you were right and wrong at the same time .... NO CURRENT FLOW that implies there is no voltage across the circuit at all ...
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Hello Sir 1-if we connect the voltmeter across R1 then it show the voltage equal to battery.Why? because ohm law is not applicable for open circuit.current wants closed path but voltage wants two terminals
the current has no path to complete both R6 and R7 is infinite, so the whole drop occur on the R1 according to kvl,
I don´t think so. Since there is nothing on earth that has infinity resistance, we cannot prove that on R1, the voltage would be 0v. Such a small value of voltage would be on R1, so the answer from my point of view should be something like '' VR1<<5V'',.
I think infinity resistance means the resistor would be an insulating substance! :-P
No current flows across R6 and R2 as R6 has infinite resistance and as R3 has 0 ohm resistance it behaves as a short circuit. Finally the circuit only has 4 resistances in it's equivalent circuit i.e. R1 in series with (R5,R4 in parallel) which is in series with R7.
Now, the equivalent resistance of the circuit is 9.71 ohm and the overall current in the circuit is 0.51 Amperes. Hence the options ruled out are the current cannot be 5/2 anywhere in the circuit and the maximum power should be at R7 and not at R5( Power = I^2 * R which is maximum at R7). Hence the option all of these is also not possible and the only option left is voltage across R1 is 5 volt.
is it so?? I guess current divides in parallel connection and voltage in series.
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Yes , current divides in parallel and voltage in series. Voltage across all resistors will be the same i.e. 5V
the node between the 2ohm and 4 ohm resistance will be an open ckt, entire voltage will drop at that node.
Hello Sir 1-if we connect the voltmeter across R1 then it show the voltage equal to battery.Why? because ohm law is not applicable for open circuit.current wants closed path but voltage wants two terminals
No current will be flowing in the circuit because of infinite ressistance in it. No current means no voltage drop in the sorce voltage
Muhammad Arslan: Thanks for the brain Teaser.. But first correct the problem.
Well, I am assuming two cases: Case 1. When R5= infinte. R5---R7 branch and the R3---R4 and R2 branches has no meaning and is open circuit. Entire voltage will drop at R6 with zero power disspation in R1.
case2: When R5=3 ohm:
Entire Voltage will drop in R6 and R7 (both being infinite).. Equivalent (R2,R3)=R3=0, Eq(R4,(R2,R3))=R4= 4 ohm. Eq (R5, (R4,(R2,R3)) ) = some finite value..
I hope you have understood now..!!
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Hello Sir as current is not flowing through R7 it means this is an open circuit and in open circuit resistance doesn't matter on the circuit because no current flow and whatever we say R5=3 or R5=8 because the final resistance (R7) is at infinity.
Correct
The circuit is a open circuit, so no current will flow at all. No current means no power dissipation.