Magnifying Glass: 5 cm Focal Length, Object at 4 cm
A magnifying glass with 5 cm focal length and object at 4 cm (inside focal point) produces a virtual, upright, magnified image at −20 cm.
How to use this tool
- Enter focal length f, object distance dₒ and image distance dᵢ in the fields above.
- Results update instantly as you type — or click Calculate.
- Read your image distance dᵢ and the full breakdown beneath it.
When an object is placed inside the focal point of a convex lens, it acts as a magnifying glass and produces a virtual image on the same side.
Frequently asked questions
- What is the sign convention?
- Using the standard convention: distances are positive on the same side as the outgoing light (real image), negative on the same side as the incoming light (virtual image). Converging lenses have f > 0; diverging lenses f < 0.
- What happens when the object is at the focal point?
- The image distance becomes infinite (parallel outgoing rays) — no focused image forms.