I'm working through the book "Starting Electronics 2nd Edition" by Keith Brindley.
Apart from the fact that I'm sitting with pages falling out of the book all around me (really bad binding) the math has me a little confused.
The formula for calculating 2 resistors in parallel is simple enough:
(R1 x R2) / (R1 + R2)
The book then tells me that this will not work for calculating resistance for more than 2 resistors in parallel?
So (R1 x R2 x R3) / (R1 + R2 + R3) won't work?
Neither should (R1 x R2 x R3 x R4 x R5) / (R1 + R2 + R3 + R4 + R5) right?
But the long calculation that he says I need to use looks like the same thing...
Step 1: R1 x R2 = x
Step 2: R1 + R2 = y
Step 3: x / y = Resistance
Book quote "If there are only two resistors in parallel, you don't have to calculate it the way we've just done here - there is a simpler way, given by the expression: (R1 x R2) / (R1 + R2). But if there are three or more resistors in parallel you have to use the long method, I'm afraid."
It's hard to show exactly the way the book has them so please find attached a scan of the book pages below.
Apart from the fact that I'm sitting with pages falling out of the book all around me (really bad binding) the math has me a little confused.
The formula for calculating 2 resistors in parallel is simple enough:
(R1 x R2) / (R1 + R2)
The book then tells me that this will not work for calculating resistance for more than 2 resistors in parallel?
So (R1 x R2 x R3) / (R1 + R2 + R3) won't work?
Neither should (R1 x R2 x R3 x R4 x R5) / (R1 + R2 + R3 + R4 + R5) right?
But the long calculation that he says I need to use looks like the same thing...
Step 1: R1 x R2 = x
Step 2: R1 + R2 = y
Step 3: x / y = Resistance
Book quote "If there are only two resistors in parallel, you don't have to calculate it the way we've just done here - there is a simpler way, given by the expression: (R1 x R2) / (R1 + R2). But if there are three or more resistors in parallel you have to use the long method, I'm afraid."
It's hard to show exactly the way the book has them so please find attached a scan of the book pages below.