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.

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.

Gurcharn said:   7 years ago
I think 600 mA.

VISHAL said:   7 years ago
Nice explanation @Pankaj.

Damchi said:   8 years ago
Loop1: V =i1(R1+R2) - i2R2.
=> 21=40i1-35i2 ---------1.

Loop2: - i1R1+i2(R2+R3) =0.
=> - 35i1+49i2=0.
=> i1=(49/35)i2=(7/5)i2-------2.

Solving 1 and 2,
i2 = 1 A
i1 = 1.4 A.

Current through R2 = i1-i2
= 0.4 A = 400 mA.

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

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

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.


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