Ray Diagram Simulator: Lenses & Mirrors

Classroom worksheet · Interactive simulation: https://lkforge.com/tools/physics/geometric-optics/

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Learning objectives

Construct ray diagrams for converging and diverging lenses and mirrors.
Relate object distance and focal length to image position, size, and orientation.
Distinguish real from virtual images.

Variables to change

Lens/mirror type
Focal length
Object distance
Object height

Procedure

Select a converging (convex) lens and place the object beyond twice the focal length (2f).
Move the object to between f and 2f, then to inside the focal point (closer than f).
Switch to a diverging (concave) lens and observe the image for any object distance.
Record whether each image is real or virtual, upright or inverted, magnified or reduced.

Observations

For each configuration note the image distance, magnification, orientation, and whether the image is real or virtual.

Questions

With a converging lens and the object beyond 2f, describe the image.
What happens to the image as the object moves toward the focal point?
When the object is inside the focal length of a converging lens, what kind of image forms?
Can a diverging lens ever form a real image of a real object?
Write the thin-lens equation and the magnification relation.

Answer key (instructors)

1. Real, inverted, and reduced, located between f and 2f on the far side.
2. The image moves farther away and grows larger; at the focal point no clear image forms (rays emerge parallel).
3. A virtual, upright, magnified image on the same side as the object — this is how a magnifying glass works.
4. No. A diverging lens always forms a virtual, upright, reduced image.
5. 1/f = 1/do + 1/di, and m = -di/do = hi/ho.

Ray diagrams predict images by tracing standard rays through a lens or mirror. Converging optics can make real, inverted images or, for close objects, virtual magnified ones; diverging optics always make virtual, reduced images. The thin-lens equation quantifies the same results.