# Electronics - Parallel Circuits - Discussion

Discussion Forum : Parallel Circuits - General Questions (Q.No. 25)

25.

Which component is open?

Discussion:

17 comments Page 1 of 2.
Sasi said:
1 decade ago

If R3 get open means R4 also opened.

So, we can get a maximum output.

So, we can get a maximum output.

Krishnan said:
1 decade ago

I don't understand its meaning.

Deepti said:
1 decade ago

Total current = 21mA

Current through R1 & R2 = 18mA

So it needs R1 & r2 equivalent = 2/3 which is true.

So R1 R2 not open

Now total voltage acrros last branch = 12v

which is given by R4 ( 4Kohm * 3mA)so there is no need of R3

Hence it is opened.

Current through R1 & R2 = 18mA

So it needs R1 & r2 equivalent = 2/3 which is true.

So R1 R2 not open

Now total voltage acrros last branch = 12v

which is given by R4 ( 4Kohm * 3mA)so there is no need of R3

Hence it is opened.

Gopiram Verma said:
1 decade ago

Good explanation deepti.

Hanish said:
1 decade ago

Super deepi.

Sreeyush Sudhakaran said:
1 decade ago

It=I1=0.021A

I3=0.003A

IR1=12/1K=0.012A

IR2=12/2K=0.006A

IR3=12/3K=0.004A

IR4=12/4K=0.003A

here we can see that IR4=I3 (0.003A) ie no current is flowing through R3

Also It=IR1+R2+IR3+IR4=0.012+0.006+0.004+0.003=0.025 Which is

not correct.

By open circuiting R3 we get It=0.012+0.006+0.003=0.021 which is correct.

So R1 is open in the circuit

I3=0.003A

IR1=12/1K=0.012A

IR2=12/2K=0.006A

IR3=12/3K=0.004A

IR4=12/4K=0.003A

here we can see that IR4=I3 (0.003A) ie no current is flowing through R3

Also It=IR1+R2+IR3+IR4=0.012+0.006+0.004+0.003=0.025 Which is

not correct.

By open circuiting R3 we get It=0.012+0.006+0.003=0.021 which is correct.

So R1 is open in the circuit

Kishu said:
1 decade ago

Answer R1 is open because current not flow in R1 because there is short circuit across R1 current always flow in low resistive path.

Saurabh said:
1 decade ago

This is not clear how R3 is open connection means only one pole is connected.

Subedar Sk shakya said:
1 decade ago

As we know in parallel circuits current divides& voltage remains same here the first amp meter shows 0.021A is the total current flowing through the R1,R2,R3,R4 and second one shows the current flowing through R3&R4

Now current reading for first one r1*r2/r1+r2=1*2/1+2 =2/3 I=V/R so(12)/(2/3)= 18ma now remains 3ma for second one so it clearly shows again I= V/R =12/4k=3ma So no need of R3.

Here R3 is Open.

Now current reading for first one r1*r2/r1+r2=1*2/1+2 =2/3 I=V/R so(12)/(2/3)= 18ma now remains 3ma for second one so it clearly shows again I= V/R =12/4k=3ma So no need of R3.

Here R3 is Open.

JAGANADHAN.R said:
1 decade ago

Hi,

Total current = 21mA.

Current required by R1 and R2 = 18mA.

So for remaining 3mA(21mA -18mA), R4 = 4K is enough no need for R3.

Thank you.

Total current = 21mA.

Current required by R1 and R2 = 18mA.

So for remaining 3mA(21mA -18mA), R4 = 4K is enough no need for R3.

Thank you.

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