Discuss Parallel cables in the Industrial Electrician Talk area at ElectriciansForums.net

Welcome to ElectriciansForums.net - The American Electrical Advice Forum
Head straight to the main forums to chat by click here:   American Electrical Advice Forum

M

me1

Help with calculation please.

If separate cable measure : 10Ω, 5Ω, 5Ω, 4Ω and 2Ω what would it be in parallel?

I get this so far


1 1 1 1 1 1 = What happens next?
10 + 5 + 5 + 5 + 4 + 2
 
1/Rt = 1/R1 + 1/R2 + 1/R3 +1/R4 + 1/R5., so 1/Rt = ?????, then Rt = ?????

you've got 3 5's there instead of 2.

answer is 0.8. show your workings.
 
Sorry there should be two 5s.

I am not sure how you get the result, would you mind showing me please?

Much appreciated

R/1= 1/10+1/5+1/5+1/4+ 1/2 =
 
And don't forget the initial answer will be a reciprocal, ie. 1/r so don't forget the last divide - a lot of people forget this. Tel, I know your answer covers this but thought I'd emphasize it. Daz
 
Find the common denominator of your resistors

work out how many times each of your resistor values go into your common denominator and add them all together

then divide your common denominator by what answer you get from above

Hope that makes sense lol !
 
Just use a scientific calculator and as been mentioned, don't forget to reciprocate (1/x or x-1 button) after summing the fractions.
 
R1 = 10 Ω
R2 = 5 Ω
R3 = 5 Ω
R4 = 4 Ω
R5= 2 Ω

1/Rt = 1/R1 + 1/R2 + 1/R3 = 1/R4 +1/R5

1/Rt = 1/10 + 1/5 + 1/5 + 1/4 + 1/2

You can do this on a calculator using the M+ function
1/10=M+, 1/5=M+,1/5=M+, 1/4 =M+, 1/2=M+
Mr
1/x

You can do this in your head with decimals
1/10= 0.1, 1/5= 0.2, 1/5= 0.2, 1/4 = 0.25, 1/2 = 0.5
0.1 + 0.2 + 0.2 + 0.25 + 0.5 = 1.25
1/1.25 = 4/5 =0.8

You can add the numbers using the common denominator (20)
To give 2/20 + 4/20 + 4/20 + 5/20 + 10/20 = 25/20
1/ (25/20) =20/25 = 4/5 = 0.8
 
For something as simple as this calc I would do it using the last method......in mi yed.

Then again, it depends on age, capability and learning methods
 
But just to add:

A useful double check after you have calculated is to remember that your answer will always be a value lower than the lowest resistor in any parallel group - in this case < 2 ohms
 
Last edited by a moderator:
also useful to remember, although not really related is for capacitors in parallel , you just add them, but in series use the reciprocal method as for parallel resistors.
 

Reply to Parallel cables in the Industrial Electrician Talk area at ElectriciansForums.net

OFFICIAL SPONSORS

Electrical Goods - Electrical Tools - Brand Names Electrician Courses Green Electrical Goods PCB Way Electrical Goods - Electrical Tools - Brand Names Pushfit Wire Connectors Electric Underfloor Heating Electrician Courses
These Official Forum Sponsors May Provide Discounts to Regular Forum Members - If you would like to sponsor us then CLICK HERE and post a thread with who you are, and we'll send you some stats etc
This website was designed, optimised and is hosted by Untold Media. Operating under the name Untold Media since 2001.
Back
Top
AdBlock Detected

We get it, advertisements are annoying!

Sure, ad-blocking software does a great job at blocking ads, but it also blocks useful features of our website. For the best site experience please disable your AdBlocker.

I've Disabled AdBlock