The radiii of curvature of a double convex lens are 30 cm and 60 cm and the refractive index of its glass is 1.5. Calculate the focal length of the lens.
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As We know the radii of the curvature of a double convex lens are 30 cm and 60 cm.
- Refractive index (μ) of its Glass is 1.5 as well.
- R₁ and R₂ is 30cm and 60cm.
»Now By using Formula,
→ 1/f = (μ – 1) (1/R₁ – 1/R₂)
→ (1.5 – 1)(1/30–1/60)
→ (0.5)(2–1/60)
→ (0.5)(1/60)
→ 1/120
→ 120
Hence,
The Focal length of the double convex lens will be 120 cm.
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