Question

When a wire of 80 resistance is bent in the form of a circle then find out the resistance between any two ends of the diameter.

Answer 1

When resistor is folded into the circular form, then across diameter, for equivalent resistance, shape is divided in two parts, therefore resistance becomes half.
$R_1=\frac{8}{2}=4\Omega ,R_2=\frac{8}{2}=4\Omega$
On connecting them in parallel.
$R=\frac{R_1\times R_2}{R_1+R_2}=\frac{4\times 4}{8}=2\Omega$