How it works
Use converging thin lens with the units stated beside the fields. This form solves for positive focal length; enter the known quantities in Real object distance, Real image distance.
Inputs and units
| Input | Example value | What to enter |
|---|---|---|
| Real object distance | 0.30000000000000004 m | Formula symbol: u. Required unit: m. Must be greater than zero. |
| Real image distance | 0.44999999999999996 m | Formula symbol: vᵢ. Required unit: m. Must be greater than zero. |
Worked example
Show example inputs and results
This example is generated by the same calculation engine using the starting values in the form. Your own inputs produce your own result.
- Real object distance
- 0.30000000000000004 m
- Real image distance
- 0.44999999999999996 m
Complete example results
- Positive focal length
- 0.18 m
Reading the result
The result solves for positive focal length from the entered quantities. Check the result unit and the formula conditions before using it.
Questions and answers
Can I use the example values for my own calculation?
The example values illustrate the calculation. Replace every input with your own information, especially dates, rates and the selected operation.
When can I use the positive focal length result?
This model uses positive magnitudes. This is the real-object, real-image branch of a converging thin lens; both distances exceed focal length. Measure from the lens in one unit; virtual images and thick lenses are excluded.
Why are some results rounded?
Results display up to 8 decimal places. Calculations use the unrounded values; very small values use scientific notation. JavaScript floating-point arithmetic can introduce tiny rounding differences.
Are my inputs sent to a server?
The calculator processes inputs in your browser. Its code does not send your values to a server.
Method sources: openstax.org