- #1

arhzz

- 268

- 52

- Homework Statement
- Solve for the current Ik

- Relevant Equations
- Superposition theorem

Hello! Consider this circuit

Now I want to calculate the current Ik. The values are given as follows;

Uq1 = 12 V

Uq2 = 18V

R1 = R2 = 8 Ohm

R3 = R4 = 20 Ohm

My approach was using the Superposition theorem. First I deactived Uq2 and left Uq1 active.

Now if I am not mistaken the resistors R2 R3 and R4 should be short circuited since the current will go through the 0 Ohm wire. That would mean that the current can simply be calculated

$$ I_k' = \frac{U_{q1}}{R1} $$ that should be ##I_k' = 1,5A ##

Now if we deactivate Uq1 and leave Uq2 only R2 should remain,the rest should be short circuited.

$$ I_k'' = \frac{U_{q2}}{R2} $$ that should be ##I_k'' = 2,5 A ##

Now we can simply add these two together but I think that the direction of ## I_k'' ## is opposite of Ik since drawn in the picture,since the current is flowing in the opposite direciton of where the arrow at Uq2 is pointing,that will mean that they will colide so it should be -2,5A

That gives us ## I_k = 1,5 - 2,5 = 1,5 A ##

Now I am not sure if the way I solved it was correct.Are my assumptions that the resistors are short circuited correct?

If not how could I solve this otherwise?

Many thanks!

EDIT: I just realized that I input the wrong value for Uq2; its not 18V but rather 20V.

Also the value for ##I_k ## is also wrong it should be ## I_k = -1A ##.

Now I want to calculate the current Ik. The values are given as follows;

Uq1 = 12 V

Uq2 = 18V

R1 = R2 = 8 Ohm

R3 = R4 = 20 Ohm

My approach was using the Superposition theorem. First I deactived Uq2 and left Uq1 active.

Now if I am not mistaken the resistors R2 R3 and R4 should be short circuited since the current will go through the 0 Ohm wire. That would mean that the current can simply be calculated

$$ I_k' = \frac{U_{q1}}{R1} $$ that should be ##I_k' = 1,5A ##

Now if we deactivate Uq1 and leave Uq2 only R2 should remain,the rest should be short circuited.

$$ I_k'' = \frac{U_{q2}}{R2} $$ that should be ##I_k'' = 2,5 A ##

Now we can simply add these two together but I think that the direction of ## I_k'' ## is opposite of Ik since drawn in the picture,since the current is flowing in the opposite direciton of where the arrow at Uq2 is pointing,that will mean that they will colide so it should be -2,5A

That gives us ## I_k = 1,5 - 2,5 = 1,5 A ##

Now I am not sure if the way I solved it was correct.Are my assumptions that the resistors are short circuited correct?

If not how could I solve this otherwise?

Many thanks!

EDIT: I just realized that I input the wrong value for Uq2; its not 18V but rather 20V.

Also the value for ##I_k ## is also wrong it should be ## I_k = -1A ##.

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