Voltage across resistors - Series & Parallel

[technician]

The resistors 330, 470 and 560 are in parallel... you do not simply add these to get the combined resistance.
A little tip... the combined resistance of a parallel combination MUST be LESS THAN the value of any resistor in the parallel combination... the combined resistance must be less than 330

 

[lloydowen]

The resistors 330, 470 and 560 are in parallel... you do not simply add these to get the combined resistance.
A little tip... the combined resistance of a parallel combination MUST be LESS THAN the value of any resistor in the parallel combination... the combined resistance must be less than 330

So then do I do R234 Rt = 1/330 + 1/470 + 1/560 ?

 

[lloydowen]

Meaning 144Ohms x 9.578mA which gives me 1.379V which is what PCbwizard calculated :) :)

 

[lloydowen]

So how now do I go about finding the currents I2 - I4 ?

 

[technician]

You have got it... can you now calculate the current in each of the parallel resistors
You know the voltage across the parallel combination... it is the same for each resistor... just use V = I x R
You should find that the three currents add up to 9.578mA

 

[lloydowen]

So now I've done V2 (1.379V)/R2(330Ω)

which gave me 4.18mA... does that sound reasonable ?

 

[technician]

You have done it... do exactly the same for the 470 and 560 resistors
You should get the 3 currents are 4.18mA, 2.9mA and 2.4mA which add to 9.48mA (near enough with rounding off)
Well done

 

[lloydowen]

I have done it! :) Thanks guys so much help! I've actually learned something :P Is there a way I can say thanks on this forum like a +1 rep or?

 

[gneill]

I have done it! :) Thanks guys so much help! I've actually learned something :P Is there a way I can say thanks on this forum like a +1 rep or?

Well done lloydowen. The best way to thank us is to ace your next exam! If you have comments you wish to make about your experience here, there's always the "Forum Feedback & Announcements" forum in the PF Lounge area.

 

[lloydowen]

I will be sure to write in there! I'm taking Electrical Engineering and I have an exam monday so I'll hopefully be good for it! :P

 

[technician]

Keep coming back...you get a variety of approaches... we love helping