Electronics - Series-Parallel Circuits - Discussion

Discussion Forum : Series-Parallel Circuits - General Questions (Q.No. 8)
8.
With 21 V applied, if R1 = 5 ohms, R2 = 35 ohms, and R3 = 14 ohms, what is the current of R2 if R1 is series connected with parallel circuit R2 and R3?
200 mA
800 mA
600 mA
400 mA
Answer: Option
Explanation:
No answer description is available. Let's discuss.
Discussion:
22 comments Page 2 of 3.

Lester said:   9 years ago
Not getting, please explain the solution.

Kamran said:   9 years ago
Thanks @Pankaj.

P@$hoo said:   9 years ago
Nice explanation @Pankaj.

Happy said:   9 years ago
Thanks, @Pankaj. Your explanation is very nice.

Deepthi said:   9 years ago
Thanks @Pankaj.

Chinmay said:   10 years ago
I satisfied with your explanation.

Pankaj said:   1 decade ago
1st calculate the total Resistance.

Rt = R1+R2||R3.

= 5+(35*14)/35+14 = 15.

According to voltage divider:

Voltage across R1 is V1 = v*R1/Rt.

V1=21*5/15=7.

Then voltage across the parallel circuit is 21-7=14;

Then current across I2 = 14/R2 = 14/35 = 0.4 A or 400 mA.
(2)

Jhedd said:   1 decade ago
It is the total resistance.

James Adams said:   1 decade ago
Where did the 15 ohms come from?

Orange said:   1 decade ago
By applying mesh analysis at each loop.

40I1-35I2=21---->eqn(1).
-35I1+49I2=0----->eqn(2).

RESOLVING BOTH WE GET,

I1=1.1amp and I2= 1.5amp.
current at R2 is I1-I2 =====> 1.5-1.1=0.44amp=400mA.


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