Question

a wire of resistance 25W is bent in form of a circle .What is resistances b/w two points at the end diameter of the circle

Answer 1

here W is incorrectly used.
if it is 25 ohm then solution is as follows.
since circular wire will be divided in to 2 equal lengths.
and both l/2 lenth's wire will be in parallel combination.
since l lenth's wire's resistance is 25 ohm then l/2 length wire's resistance will be =25/2=12.5 ohm
since r is proportional to l if area remains same
now applying parralel combination.
1/r=1/r1 +1/r2
or r=r1*r2/(r1+r2)
r=12.5*12.5/(12.5+12.5)
=12.5*12.5/25 =6.25 ohm
i hope you understood the matter otherwise you can ask me again.