Question

A uniform metal wire of length \(l\) has 10 Ω resistance. Now this wire is stretched to a length \(2l \) and then bent to form a perfect circle. The equivalent resistance across any arbitrary diameter of that circle is :

• A. 10 Ω
• B. 5 Ω
• C. 40 Ω
• D. 20 Ω

Answer 1

The Correct Option is A

Let R₀ be initial resistance = 10 Ω. When stretched to length 2l, the resistance becomes R₁ = $\frac{2l}{l}$R₀ = 20 Ω. When bent into a circle, the total resistance remains 20 Ω.

The resistance of the semi-circle along any diameter is given by 20/2 = 10 Ω.