Physics · Grades 10–12
Thin lenses and image conventions · Revision sheet
Use one sign convention and avoid claims that every convex lens image is real.
Learn the idea
Thin-lens model
For a converging lens with a real object beyond the focal point, positive real distances satisfy 1/f = 1/do + 1/di.
Real image
Rays actually converge at a real image, which may be formed on a screen.
Virtual case
An object inside the focal length of a converging lens produces a virtual image in the elementary model.
Magnification
Image size and orientation are different. Specify whether a signed magnification or its magnitude is requested.
Explain without looking
- A learner says a larger image must be real. Explain the mistake.
- What distance cannot be inserted as a finite ordinary image distance when a real object is at the focal point in the ideal model?
Further reading and review references
These are reference links, not copied exercises, institutional endorsement or proof of independent review.
Independent educational review required. Grade bands are approximate; these are not officially aligned curricula.