Electronics-Lab.com Community

# Paralell resistors

## Recommended Posts

I recently found out that if you have resistors of the same value wired in paralell, the resistance is lower than one of the resistors in the paralell. For example, if you have 2 resistors that are 50 ohms each, wire them in paralell and their resistance is 25 ohms each. I don't understand how having resistors in paralell will lower resistance. Can someone tell me why the resistance divides by 2 when you add 2 resistors of the same value?

Thanks a ton.

##### Share on other sites

Hi,

E-Lab has this link for you: http://www.electronics-lab.com/articles/files/dc_circuits_lecture.pdf
Paralleled resistors on page 5.

##### Share on other sites

Any number of resistors of the same value in parallel is equal to the resistor value divided by the number of resistors, it's not just limited too 2... i.e. 10, 100ohm resisistors in parallel is 100/10=10ohms... it's one of those things that works out that way given certain conditions.

The equation for any values in parallel is Rval= 1/ (1/R1+1/R2...1/Rn). I suppose you could algebraically manipulate the equation to get Rval=R1/n when R1=R2=R3... if you wanted to really prove it to yourself.

##### Share on other sites

COZ 2 FIND TOTAL RESISTNCE WHEN NO OF RESISTORS R CONNECTED IN PARALLEL THERES A FORMULA ; 1/R = 1/R1 +1/R2 + . . . +1/RN

##### Share on other sites

Hi,

a helpful formula to know when u are only finding the resistence of only 2 resistors in parallel is

Rt= (R1*R2)/(R1+R2)

Ohm's Law......

##### Share on other sites

I believe you are confused because you stated that two 50 Ohm resistors in parallel causes them to become 25 Ohms each. This is incorrect. They stay 50 Ohms each, but the resistance of the whole becomes 25 Ohms.

A single water pipe has a certain resistance to flow, but two such pipes permit twice as much flow. The same principle applies with electrical resistance. Two identical parallel paths provide half the total resistance that one would provide.

Bugger. Sorry Zeppelin.

##### Share on other sites

No. I said sorry because I had just realised I repeated exactly what you said.

##### Share on other sites

yeah, I was refering to how does it work physically, but its nice to know the math. Thanks a ton everyone, I get it now ;D.

##### Share on other sites

Can't believe something in basic electronics got so much attention, confusion.  :)

##### Share on other sites

• 3 weeks later...

an alternate path for the current to flow.
more the number of paths ,more free is the flow and hence lesser resistance!

## Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

×   Pasted as rich text.   Paste as plain text instead

Only 75 emoji are allowed.

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×