title: Ray theory analysis of the shadow blister effect.
abstract: When an extended light source such as the Sun illuminates two objects so that their shadows lie close to each other, the shadow of one of the objects occasionally appears to bulge out toward the shadow of the other. This effect is caused by the overlap of the penumbras of the shadows and is analyzed here with ray theory. A laboratory demonstration of this phenomenon is performed and compared with theoretical predictions.
authors.affiliation: Department of Physics, Cleveland State University, Cleveland, Ohio 44115, USA.
authors.forename: J A
authors.initials: JA
authors.lastname: Lock