Hi all, In calculating parallel resistance, with two resistors, I have always seen the above formula written at RT = R1R2/(R+R2). What is the meaning of the || in the expression R1||R2.

Thanks

 

Exactly that.
R1 || R2 means R1 in parallel with R2.

1/Reffective = 1/R1 + 1/R2

Reffective = R1 || R2

 

Thanks for the quick answer

 

As MrChips indicated, the '||' is just a shorthand notation for "in parallel with". Think of it as being two parallel lines used to convey that notion.

It does NOT mean that you divide the product of the two values by the sum of the two values. It is not a mathematical operator of some kind.

For resistors and inductors, parallel components happen to combine that way, but for capacitors,

C1 || C2 is simply C1+C2

 

BTW, always keep in mind this: provided that R1 and R2 have different values, the equivalent R is always smaller than the smallest.

 

BTW, always keep in mind this: provided that R1 and R2 have different values, the equivalent R is always smaller than the smallest.

But also never less than half the smallest -- sometimes that's very handy to know when estimating upper and lower bounds.