Am I on the right track?

[manda]

Hi guys
Can you tell me if I'm getting this right, and if not can you see where I'm going wrong?

I have a dc circuit made up of: R1 6ohms and R2 14 ohms, connected in series,
R3 9ohms, R4 22ohms in parallel and also R5 6 ohms R6 6 ohms and R7 6 ohms also in parallel. The supply is 300v.

Total resistance I calculate as 18.8 ohms?

Total current I calculate 268.3 A

Voltage drop across R1 and R2 300v

Voltage drop across R3 and R4 0v

Voltage drop across R5 R6 and R7 0v

I get the feeling I'm totally off track though please can you advise?
cheers.---

 

[Sintra]

I work out total resistance to be 28.4 ohms.

14 ohms & 6 ohms in series = 20 ohms
9 ohms & 22 ohms in parallel = 6.4 ohms
6 ohms, 6 ohms & 6 ohms in parallel = 2 ohms

 

[manda]

Thanks Sintra.---

 

[manda]

I'm lost, would total current be 106.2A

 

[j.mawer]

If I read your description correctly you have

+300V --| R1 |---- | R2 | --- | Rp1 | ---- | Rp2 |--- 0V

Where Rp1 is R3 in parallel with R4
and Rp2 is R5 R6 R7 in parallel
R1 = 6ohm
R2 = 14 ohm
1/Rp1 = 1/9 + 1/22 SO 1/Rp1 = 0.1556 i.e. Rp1= 6.4
1/Rp2 = 1/6 + 1/6 + 1/6 SO 1/Rp2 = 3/6 i.e Rp2 = 2
Total Resistance between 300V and 0V = 6 + 14 +6.4 + 2 =28.4

This agrees with sintra so I guess he interprets the circuit the same as me

So I=V/R = 300/28.4 = 10.6A

Volt drop across resistors
V = IR
so
across R1 V=10.6 * 6 = 63.6V
across R2 V=10.6 * 14 = 148.4V
across (R1 and R2) = 212V
across Rp1 = 10.6 * 6.4 67.8V
across Rp2 = 10.6 * 2 = 21.2 V


Hopefully thats clear

 

[manda]

Thanks alot. That makes sense. ---