A wire of resistance 20 Ω is bent to form a complete circle. What will be its resistance between two diametrically opposite points?

5 Ω

The correct answer is Option (4) → 5 Ω

Total resistance of the wire = $20 \ \Omega$.

When bent into a circle, each semicircle has resistance = $\frac{20}{2} = 10 \ \Omega$.

The two semicircles are connected in parallel between diametrically opposite points.

Equivalent resistance $R = \frac{10 \times 10}{10 + 10} = \frac{100}{20} = 5 \ \Omega$.

Answer: $5 \ \Omega$