// optics · 1/f = 1/v − 1/u

Ray Optics

Drag the object arrow to change distance — use the toolbar to switch element type
Focal length 8 cm
Object height 3 cm

Study the ray diagram above, then calculate the answer below.

About Ray Optics

  1. Choose an element. Use the toolbar to switch between convex lens, concave lens, concave mirror, and convex mirror.
  2. Drag the object. Click and drag the yellow arrow to change the object distance. The three principal rays update in real time.
  3. Adjust focal length. Use the slider below the canvas to change the focal length of the element.
  4. Read the analysis. The side panel shows object distance, image distance, magnification, and image nature (real/virtual, upright/inverted).
  5. Ray colors. Red ray is parallel then through focus. Green ray passes through the center. Blue ray goes through focus then exits parallel.
  6. Practice mode. Switch to Practice to solve randomly generated optics problems — find image distance, magnification, or focal length.
Tip: Try dragging the object past the focal point of a convex lens to see the image flip from virtual to real!