# ResistanceWatch

Announcements
This discussion is closed.
#1
For resistance in parallel, the equivalent resistance is always smaller than the smallest resistance and for resistance in series, the equivalent resistance is always larger than the larger resistance. why is this so ???
0
14 years ago
#2
Because of the way you sum resistances. In series R = r1 + r2 + r3, whereas in parallel 1/R = 1/r1 + 1/r2 + 1/r3

Now in the first case the sum of a load of positive numbers is always going to be bigger than the largest one. In the second case the inverse of a sum of positive numbers is always going to be smaller than the largest, and the largest inverse is the smallest resistance.
0
14 years ago
#3
Or to put it another way, if you think of a resistor like a narrow path which the current has to get through, then a series path is long and hard to pass through, whereas with parallel, two paths side by side are easier than one.
0
14 years ago
#4
tis a long worded question. cut out the waffle, get a good revision guide, or read your notes again. Or then again you could get the geniuses on here to do it for you
0
X
new posts
Back
to top
Latest
My Feed

### Oops, nobody has postedin the last few hours.

Why not re-start the conversation?

see more

### See more of what you like onThe Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

### University open days

• University of East Anglia
Sun, 20 Oct '19
• University for the Creative Arts
Sun, 20 Oct '19
• University of Gloucestershire
Sun, 20 Oct '19

### Poll

Join the discussion

Yes I know where I'm applying (86)
67.72%
No I haven't decided yet (25)
19.69%
Yes but I might change my mind (16)
12.6%