S5 Physics: Lenses, Lens Formula and Magnification

These Senior 5 Physics Paper 2 notes from Trinity College Nabbingo cover lenses in geometrical optics. They derive the relationship between object distance, image distance and focal length using small-angle approximations. The notes define linear magnification and develop expressions linking it to image distance, object distance and focal length. They also derive a thin-lens expression involving refractive index and surface radii of curvature. Sign conventions for focal length, object and image distances, and curvature are listed. An exercise asks learners to derive the lens formula for a diverging lens.