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Anybody know anything about series circuits?

12K views 48 replies 10 participants last post by  ohiohomedoctor 
#1 ·
Getting caught up on class work.

Can somebody explain this relationship/formula in plain English? I thought it would come back to me since I was an EM3 in the USCG but nada.

Rt= 20ohms It= 5A Et= 100V Pt=500W
R1= 5ohms I1= 5A E1= 25V P1=125W
R2= 10ohms I2= 5A E2= 50V P2= 230W
R3= 5ohms I3= 5A E3= 25V P3= 125W

Any advice appreciated!:thumbsup:
 
#4 · (Edited)
Rt= 20ohms It= 5A Et= 100V Pt=500W
R1= 5ohms I1= 5A E1= 25V P1=125W
R2= 10ohms I2= 5A E2= 50V P2= 230W
R3= 5ohms I3= 5A E3= 25V P3= 125W

Resistant total = 20 ohms, Current total = 5 amps, Voltage total = 100v, Power total = 500w

R1+R2+R3=Rt
In a series circuit the current is constant
25v+50v+25v= 100v (Et)
125W+250W+125W=500W (there is an error in your statement, 5Ax50v=250W)

I x E = P
E / I = R

You can move these equations around to suit your need and figure out the missing data

P/E=I
P/I=E

R/E=I
R/I=E

Any more questions?:whistling
 
#9 ·
Rt= 20ohms It= 5A Et= 100V Pt=500W
R1= 5ohms I1= 5A E1= 25V P1=125W
R2= 10ohms I2= 5A E2= 50V P2= 230W
R3= 5ohms I3= 5A E3= 25V P3= 125W

Resistant total = 20 ohms, Current total = 5 amps, Voltage total = 100v, Power total = 500w

R1+R2+R3=Rt
In a series circuit the current is constant
25v+50v+25v= 100v (Et)
125W+250W+125W=500W (there is an error in your statement, 5Ax50v=250W)

I x E = P
E / I = R

You can move these equations around to suit your need and figure out the missing data

P/E=I
P/I=E

R/E=I
R/I=E

Any more questions?:whistling
Check out the head on Leo:clap::clap::clap:
 
#5 ·
Holy hell. Ummm, this is harder than I thought.

Here's the one I'm trying to solve now:

Rt= ?ohms It= ?A ET= ?V Pt= 625W
R1= ?ohms I1=?A E1= ?V P1= ?W
R2= 100 ohms I2= 2A E2= ?V P2= ?W
R3= ?ohms I3= ?A E3=50V P3= ?W

I don't think I have enough data to solve that problem? Do I? I think I need more of the ? filled in so I can solve it.
 
#6 ·
So, are you asking me to give you the answer? It's gonna cost you your desert ya know. And no frik'n fruit.:laughing:
 
#7 ·
Getting caught up on class work.

Can somebody explain this relationship/formula in plain English? I thought it would come back to me since I was an EM3 in the USCG but nada.

Rt= 20ohms It= 5A Et= 100V Pt=500W
R1= 5ohms I1= 5A E1= 25V P1=125W
R2= 10ohms I2= 5A E2= 50V P2= 230W
R3= 5ohms I3= 5A E3= 25V P3= 125W

Any advice appreciated!:thumbsup:

That is just basic Ohm's Law.


From first line in example
Amps x Volts = Watts 5A x 100V = 500W
Watts / Volts = Amps 500W / 100V = 5A
Watts / Amps = Volts 500W / 5A = 100V

Volts / Amps = Ohms 100V / 5A = 20ohms
Amps x Ohms = Volts 20 ohms x 5A = 100V


The third line is wrong, should be 250 watts.



Just do a web search, there are some good sites about Ohm's Law in Series and Parallel Resistive circuits
 
#10 ·
Leo is freaking smart.

No, not asking for the answer. Just trying to get caught up on what the class is doing. Missed the first two weeks because I was having heart surgery.

I don't want to be too far behind, especially since I'll be missing more class time with radi, chemo, and more surgery.

So to fnd the t line I work back from 625 watts? TheI line is going to be 2A all the way because amperage doesn't change in a series circuit?
 
#11 ·
Rt= ?ohms It= ?A ET= ?V Pt= 625W
R1= ?ohms I1=?A E1= ?V P1= ?W
R2= 100 ohms I2= 2A E2= ?V P2= ?W
R3= ?ohms I3= ?A E3=50V P3= ?W


Ok, I'll see if I can walk you through it.

Current is constant through the system so all of the I=2A

You have 625W for the Pt and you have a current so you should be able to figure out Et

P3 is also figured out for you because you know that I=2A

Because now you know I3 and E3 you can figure out R3

Because you know R2 and I2 you can figure out E2 and then P2

Now the rest is figured out from subtraction Because you know equation 2 and 3 you just have to put in what must remain to get the total equation.
 
#16 · (Edited)
:notworthy Very good grasshopper

Now let us introduce you to variable frequency in a capacitance/impedance circuit in a 3 phase system......:shutup:
 
#17 ·
Electronic cabinet maker to the rescue.....:party:
 
#18 ·
Final answer:

Rt= 156.25ohms It= 2A Et=312.5V Pt=625W
R1= 1.25ohms I1= 2A E1= 62.5V P1= 125W
R2= 100ohms I2=2A E2= 200V P2= 400W
R3= 25ohms I3=2A E3= 50V P= 100W

I don't know how it works, but it looks rigt to me.

This is why electricians make $100+ an hour.
 
#19 ·
You got the numbers right but R1 is written wrong.
 
#20 ·
So when you get to parallel circuits just remember that the voltage is constant and the current is variable.
 
#22 ·
You need another given variable for the sequence resulting in 1. Only thing that is giving is 2a since it stays the same in a series circuit, no other variable can be found unless another given is listed. You can't find r1, e1, or p1 with just 2a.




Yes
Because you know eq 2 and 3 and part of eq total you can figure out the missing information easily. Without the other info you would be lost because you really need 2 parts of the equation to get the third part.

It would be a lot easier if this was written out as a schematic. I hate word problems.
 
#23 ·
Easiest way to do Ohms Law question:

Create a grid, or spreadsheet, with a line for each load and columns for each variable.



Put in the numbers you already know, then you can easily apply The Wheel formulas to calculate the rest.
 
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#25 ·
I laughed my ass off, I got it saved in a quote. I hate when that happens to me.
 
#27 ·
If you don't know how electrons flow or how they react under certain conditions then how will you have any practical field knowledge?

Depending on your line of electrical work will determine if you will be calculating basic formulas, do I ever do calcs on finding Rt on a residential application ? No I do not, but when I am modifying honda computers for turbocharging and n20 applications then yes. :laughing:
 
#28 ·
I was just curious. Just because I haven't seen an electrician break out a calculator on a job doesn't mean that some don't.

What would be some jobsite examples of how/when I would use this information?

Give me something I can relate it too and perhaps I can understand it better.
 
#30 ·
Example: Some wall heaters in a residence.

Do I want 120 or 240 volt heaters and what size wire and circuit do I need.

Two(2) 1500 heaters

1500 watts / 120 volts = 12.5 amps, 2 of them will draw 25 amps so pushing it with 10 gauge wire on a 30 amp circuit.

1500 watts / 240 volts = 6.25 amps, 2 will draw 13 amps so would be better of this way with 12 gauge wire on a 20 amp circuit.
 
#31 ·
Series is where everyting is hooked together. Unplug one component and nothing works.

Paralell is where everything feeds off a common source. Unplug one component and all the other stuff still works.

That sound about right?
 
#34 ·
I'm pursuing a Bachelors of Applied Science in HVAC and Appliance Technology.

With recent health problems I may scale that back to an Associates of Applied Science in HVAC and Appliance Technology.
 
#35 ·
I was just curious. Just because I haven't seen an electrician break out a calculator on a job doesn't mean that some don't.
I know I do, quite handy for some quick trig on funky bends too.

Onece you practice ohm's law enough (google it for practice problems) and understand it you will look back and feel really stupid...yet at first I could see it being rather daunting.
 
#36 · (Edited)
Right now we're also learning about forced air heat. Gas, electric, and oil fired furnaces. Next semester I believe is air conditioning. After that we get into refrigeration and appliances. Which I'm personally very excited about. I'm looking hard at buying into a Mr. Appliance franchise. I'd also like to own a Aire Serve as well. I know the guy that bought Mr. Rooter is dominating the market down here right now. The guy that bought Aire Serve in Spokane supposedly put six big HVAC cntractors under his first year in business.

I see good things if I do well in this course and get my degree.
 
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