Elongation of Wires Trick in 59 Seconds! 🔥 | JEE Physics
❓ Question Two wires A and B are made of the same material . The ratio of their lengths is L A L B = 1 3 and the ratio of their diameters is d A d B = 2. If both wires are stretched using the same force , what is the ratio of their elongations ? 🖼️ Concept Image ✍️ Short Solution This is a direct Young’s modulus application . No heavy maths — bas elongation dependence samajh lo, answer khud nikal jaata hai 😎 🔹 Step 1 — Elongation Formula (FOUNDATION 💯)** For a wire under tension: Δ L = F L Y A \Delta L = \frac{FL}{YA} Where: F F = applied force L L = original length Y Y = Young’s modulus A A = cross-sectional area 📌 Same material ⇒ same Y Y Y 📌 Same force ⇒ same F F F So, Δ L ∝ L A \Delta L \propto \frac{L}{A} 🔹 Step 2 — Area in terms of Diameter Cross-sectional area: A = π d 2 4 A=\frac{\pi d^2}{4} So: A ∝ d 2 A \propto d^2 Hence: Δ L ∝ L d 2 \Delta L \propto \frac{L}{d^2} 🧠 Golden relation to remember : El...