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Thin Lenses in Combination (Edexcel AS Physics): Revision Note

Exam code: 8PH0

Lindsay Gilmour

Last updated

Thin Lenses in Combination

  • When multiple lenses are used in series (one after the other) this is called a compound lens

  • To find the total power of a compound lens, find the sum of the powers of the individual lenses

PTotal = P1 + P2 + .... Pn

  • Where:

    • PTotal = Total power of all the lenses (dioptre, D)

    • P1 = power of lens 1 (dioptre, D)

    • P2  = power of lens 2 (dioptre, D)

5-20-thin-lenses-in-combination-illustration_edexcel-al-physics-rn

  • In this case the image is:

    • Virtual

    • Diminished

    • Upright

  • The lenses should be:

    • Arranged so that their principle axes line up

    • Touching or very close

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Lindsay Gilmour

Author: Lindsay Gilmour

Expertise: Physics Content Creator

Lindsay graduated with First Class Honours from the University of Greenwich and earned her Science Communication MSc at Imperial College London. Now with many years’ experience as a Head of Physics and Examiner for A Level and IGCSE Physics (and Biology!), her love of communicating, educating and Physics has brought her to Save My Exams where she hopes to help as many students as possible on their next steps.