A wire of resistance 10 ohm is bent in the form of closed circle. What is the effective resistance between the two points at the ends of any diameter of the circle?
When a resistance is bent in a circle, the resistors are are connected in parallel.
Each of the resistors (the 2 parallel resistors of the circle) have a resistance of 10 ohms.
So we get the following-
Req = R1 x R2 / R1R2 (where Req is equivalent resistance in parallel connections)
1/Rp =1/R1 + 1/R2 ( where Rp is resistance in parallel )
1/Rp = 1/10 + 1/10
1/Rp = 2/10
Rp = 10/2
Rp = 5 ohms