Applications: optical fibres, mirage, sparkling of diamond
Reflection and refraction · Physics
Convex lens ray diagram
Interactive 3DMove the object and watch parallel rays converge at the focal point while the image obeys 1/f = 1/v + 1/u.
Controls
Drag the sliders or type a value — the simulation updates live.
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3cm10cm
Study notes
Diamond has refractive index n = 2.42. Find its critical angle for air. Step 1: sin C = 1/n = 1/2.42 = 0.413 Step 2: C = sin⁻¹(0.413) = 24.4° This small critical angle means most light entering diamond undergoes TIR and comes back out the top — that's the sparkle!