Two thin lenses (focal lengths f₁ and f₂)are in contact.Their equivalent focal length is:

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Quizplus · Accepted Answer

When two thin lenses are in contact, their equivalent focal length can be calculated using the formula: 1/f_eq = 1/f1 + 1/f2 - d/(f1f2) where f1 and f2 are the focal lengths of the individual lenses, and d is the distance between them (which is zero in this case). Simplifying the formula for two lenses in contact with each other (i.e., d=0), we get: 1/f_eq = 1/f1 + 1/f2 Multiplying both sides by f1f2, we get: f2/f_eq + f1/f_eq = 1 Rearranging, we get: 1/f_eq = (f1+f2)/f1f2 or f_eq = f1f2/(f1+f2) Therefore, the equivalent focal length of the two lenses in contact is: f_eq = f₁f₂/(f₁ + f₂)

Two Thin Lenses (Focal Lengths F1 and F2)are in Contact

Two Thin Lenses (Focal Lengths F₁ and F₂)are in Contact