Series Parallel Circuit Help!

Studying for a Test,
Can someone please explain the answer please !!

See attachment

Since this is a student question no-one will do your work for you . But a hint is : - work out the current in each resistor .

richleva, can you show what you're getting for the answer & how you're getting it?
In addition to pal's hint, remember that at any node in a circuit, current in = current out.

Use kirchoff’s current and voltage laws.

I agree that we should not be doing your homework but since this already has the answer 4550W and you are trying to understand how they got there. A little more detail might be in order.


It looks like you started by figuring the voltage drop on R2 and R5 (labeled on attached drawing). That's the only voltages you can figure out directly.

So, now you need to figure out what current is going through the remaining resistors. I've started with one of the nodes. You know that total current at that point has to be equal to the sum of the currents, what is the current through R4? Knowing R4's current, will let you calculate R3's current since you know Load 1's current. Just keep going like that until you calculate all the currents.

Once you know all the currents you should be able to calculate the voltage drops. That will let you determine the voltage drop across all three loads. And once you know the current and voltage on each load, calculating the power for each is trivial.

Here's a video I made 5 years ago. Sorry for the quality...
https://www.youtube.com/watch?v=kIQlOulFGAk

I'm sorry . Using the sketch kindly provided by Tibert , the current through R1 is load 1 + load 2 = 30A so the power from Battery 1 is 3600 VA . The current through R5 and load 3 is 15A so the power from Battery 2 is 1800 VA . Total circuit power is 5400 VA .
If you think of R1 to R5 as "losses" , then
R1 loss is 30A thro .5 Ohm = 450VA
R2 loss is 10A thro .5 Ohm = 50VA
R3 loss is 15A thro .5 Ohm = 112.5VA
R4 loss is 5A thro .5 Ohm = 12.5VA
R5 loss is 15A thro 1 Ohm = 225VA
Total "losses" = 850W


Total load power = 5400 VA - 850 VA = 4550 VA

Classic nodal analysis question. I remember when they through it in with ac and RLC components in the circuit.

Thanks Everyone for your help on this, My boss wants me to get my electrical license. Now I need to review everything all over again, I forgot a lot of this stuff since I never used it.

PAL And Tibert Thanks again, Hopefully I can get more help moving forward

What kind of license?

james

James Mcquade said:

What kind of license?

james

Click to expand...

309A- Construction and Maintenance

Don't know if this will help any, but go to www.mikeholt.com
they have books you can buy and practice tests you can take online.

hope this helps,
james