Electronics - Parallel Circuits - Discussion

Total power reading of the wattmeter is 9.408.

If you solve for the individual powers in the branches:

P = V^2/R.
P1 = 2.304W , P2 = 1.152W , P3 = 0.768W &, P4 = 0.576W.

If you get the total power:
P1+P2+P3+P4 = 4.8 W which is smaller than the reading in the ammeter which definitely tells us that something is wrong with the circuit.

Now since there are ammeters connected in between the branches we can check if the individual values of branch currents match the readings.

First in R2, I2 = 48/2000 = 24mA.
In R3, I3 = 48/3000 = 16mA.
In R4, I4 = 48/4000 = 12mA.

From the Ammeter Connected in-branch R4 we can confirm that it is correct since it has the same reading of 0.012 or 12mA.

From the Ammeter Connection in-branch R2 the reading is 0.052 A or 52mA since we know that I2 = 24mA, via Kirchoff's Current Law 52mA=24mA+ I , I is the current that would go to the branch R3. I = 28mA.

Since we know that I3 = 16mA, Via Kirchoffs Current Law we can check that, I = I3 + I4; 28mA =16mA+12mA.

Since we confirmed that I3 and I4 is correct it also implies that the current in I2 is correct therefore all of the power ratings of P2, P3, and P4 is correct thus indicating that R1 is of the wrong value.

Anyone explain the correct answer.

P = VxIt
It = P/V = 9.408/48 = 0.196A (Total Current)

IR4 = 0.012 A (Given)

R4 = 48/0.012 = 4000 = 4K R4 is correct

IR3 = V/R3 = 48/3000 = 0.016A
IR2 = V/R2 = 48/2000 = 0.024A
IR1 = V/R1 = 48/1000 = 0.048A

IR3 = (I3-I4)
I3 = (IR3+I4)
I3 = (0.016+0.012)=0.028A

R3 = V/(I3-I4) = 48/(0.028-0.012) = 3000 = 3K R3 is correct

R2 = V/(I2-I3) = 48/(0.052-0.028) = 2000 = 2K R2 is also correct

R1 = V/(It-I2) = 48/(0.196-0.052) = 333.33ohms which is notcorrect

since R1=1000ohms = 1k from the given circuit

How the current flows, when the source is open circuited with voltmeter.

Yes, I want to know same thing. When P=VI and v=ir then howvit possible p=v/r.

@H@Ri.

Your explanation is good but please tell me power = V^/R or v/r in your explanation you describe that p=v/r. Please explain anyone.

Near r1 the negative terminal is connected to positive.

@H@Ri.

You are correct! Thanks for your explanation.

@Manikandan.

Your method is wrong because I = Net voltage/Net resistance.

Guys suppose if R1 is ok 333 ohm but problem is with R2 or R3. Then how it will be opted out which one (R2 or R3) is not correct because before R2 we have a given value 0.052 and after R3 also given 0.012 but is not given between R2 & R3.

Please explain although might not look a problem to you.