How to Calculate Thin Lens
What is Thin Lens?
Thin lens equation relates object distance, image distance, and focal length. It's fundamental to cameras, microscopes, telescopes, and corrective lenses.
Formula
The calculator applies 1/f = 1/s_o + 1/s_i
- f
- 1/s_o + 1/s_i — 1/s_o + 1/s_i
Step-by-Step Guide
- 1Enter any two of: object distance (s_o), image distance (s_i), or focal length (f)
- 2The calculator applies 1/f = 1/s_o + 1/s_i
- 3Results show lens behavior and image characteristics
Worked Examples
Input
s_o = 30 cm, f = 10 cm
Result
s_i = 15 cm, magnification = 0.5×
Real inverted image
Common Mistakes to Avoid
- ✕Confusing sign conventions for distances and focal lengths
- ✕Using lens equations without considering real vs. virtual images
Frequently Asked Questions
When do you get virtual images?
Virtual images form when the object is closer than the focal point (s_o < f); the image appears upright and magnified.
What's the difference between converging and diverging lenses?
Converging (convex) lenses have positive focal length and form real images; diverging (concave) lenses have negative focal length and only form virtual images.
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