Question

A resistor of 20 cm length and resistance 5 ohm is stretched to a uniform wire of 40 cm length. The resistance now is-

• A. 10 Ω
• B. 5 Ω
• C. 20 Ω
• D. 200 Ω

Answer 1

The correct option is C

20 Ω

As R = ρ$\frac{L}{A}$ and volume = L x A = L* πr². = Constant.

By using above equations, we get ratio as 4:1