passwella.
Menu

JAMB Physics 2003 Question 32

Question 32

Current Electricity

A wire of 5Ω resistance is drawn out so that its new length is two times the original length. If the resistivity of the wire remains the same and the cross-sectional area is halved, the new resistance is

  1. A.40Ω
  2. B.20Ω
  3. C.10Ω
  4. D.5Ω
Show the answer and explanation

Answer: B (20Ω)

Explanation

R = ρL/A. Doubling L and halving A each double R, so R = 5 × 2 × 2 = 20 Ω.