Compound Lens
Verified Calculation Engine
The online Compound Lens helps you calculate instantly and solve problems related to Optics. This tool provides accurate results using standard formulas and step-by-step calculation; you can view the formula with example in the calculator where available. Whether you are a student, teacher, or professional, this calculator simplifies complex calculations and saves time. Enter the required values below and get instant results. Results are shown clearly, with optional step-by-step explanation where applicable. The tool is free to use and works in any modern browser—no download or installation required. Bookmark this page for quick access whenever you need reliable Physics calculations.
Compound Lens: calculate the requested physical quantity from the stated inputs using 1/F=1/f₁+1/f₂−d/(f₁f₂). The page states the model assumptions, units and worked examples so the result can be checked.
- Paraxial/geometrical-optics approximation where lens/mirror equations are used. Angles are measured from the normal.
Inputs
Results
Symbols, Variables & Units
| Input | Symbol / name | Unit | Role |
|---|---|---|---|
focalLength1 | Lens 1 focal length | m | Lens 1 focal length in m. |
focalLength2 | Lens 2 focal length | m | Lens 2 focal length in m. |
separation | Separation | m | Separation in m. |
Use a consistent unit system. The Physics engine evaluates numerical inputs in the units stated beside each field; it does not silently convert incompatible dimensions.
Physics Study Guide
Concept
Geometrical and wave optics
Exam focus
Use it under the stated paraxial, thin-lens, mirror or interference approximation. Track the sign convention and distinguish angle from the normal versus the surface. In an exam, write the governing equation first, substitute values with units, and check the dimensions of the final quantity.
Common mistakes
- Do not mix units; convert all dimensional inputs to a consistent unit system before substitution.
- Check signs, directions, angles and reference points before entering values.
- Do not apply the formula outside its stated physical assumptions or boundary conditions.
How to verify your answer
Check the result against the displayed formula, expected unit and physical scale. For this calculator, also verify that the stated assumptions and limiting case are satisfied.
Model limits
This result is valid only under the assumptions stated on the calculator page. For real systems with non-ideal geometry, losses, distributed effects or relativistic/quantum corrections, use the appropriate advanced model.
Worked Examples
Worked example
Use focal length1 = 2, focal length2 = 2, separation = 0. The validated result is effective focal length = 1.
- focalLength1: 2
- focalLength2: 2
- separation: 0
- effectiveFocalLength: 1
- result: 1
Second worked example
Use focal length1 = 3, focal length2 = 3, separation = 1. The validated result is effective focal length = 1.8.
- focalLength1: 3
- focalLength2: 3
- separation: 1
- effectiveFocalLength: 1.8
- result: 1.8