Focal Length of Lens in Water — Concept in 59 Seconds! 🔥
❓ Concept 🎬 Focal Length of Lens in Water — Concept in 59 Sec Lens ko air se nikaal kar paani mein daal diya… aur suddenly focal length change ho gaya? 🤔 👉 Isme koi magic nahi — sirf relative refractive index ka game hai 🔥 🖼️ Concept Image ✍️ Short Explanation JEE mein “lens in water” wale questions numerical kam, conceptual zyada hote hain. Agar tum lens maker + relative refractive index samajh gaye, toh answer seconds mein aa jaata hai 😎 🔹 Step 1 — Lens Maker’s Formula (in Air) For a thin lens in air: 1 f air = ( μ lens − 1 ) ( 1 R 1 − 1 R 2 ) Yahaan: μ lens \mu_{\text{lens}} = refractive index of lens w.r.t air R 1 , R 2 R_1, R_2 = radii of curvature 📌 Lens ka shape fixed hota hai — curvatures change nahi hote. 🔹 Step 2 — Lens Placed in Another Medium Agar lens ko kisi aur medium (jaise water) mein rakh diya: 👉 Refractive index relative ho jaata hai: μ relative = μ lens μ medium Modified lens maker formula: 1 f medium = ( ...