Thin Lenses in Combination (Edexcel A Level Physics): Revision Note

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

P_Total = P₁ + P₂ + .... P_n

• Where:

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

  • P₁ = power of lens 1 (dioptre, D)

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

• 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