Images in Mirrors • Size, Attitude, Location, Type • Size – Is the image bigger, smaller or the same size as the object? • Attitude – Is the image right side up (upright) or upside down (inverted)?
Images in Lenses • Location – Closer than, farther than or the same distance as the object to the mirror. • Type – Is the image real or virtual? – Virtual image = an image formed by light coming from an apparent light source. Light is not arriving at or coming from the actual image location.
Terminology • • • C = centre of curvature R = radius of curvature V = vertex PA = principal axis F = principal focus f = focal length • Focal plane = rays coming from different angles will form images in the focal plane
Some Rules • All distances are measured from the vertex of a curved mirror. • Distances of real objects and images are always positive • Distances to virtual objects and images are always negative. • Heights for both objects and images above the PA are positive, heights below the PA are negative.
Converging Mirror
Diverging Mirror
Rules for Curved Mirrors • A ray that is parallel to the principal axis is reflected through (or as if it had gone through) the principal focus – real or virtual. • A ray passing through (or appearing to pass through) the principal focus is reflected parallel to the principal axis. • A ray passing through (or appearing to pass through) the centre of curvature is reflected back along the same path.