Look at a flat mirror, then at the back of a spoon, then at the front. Each shows you a different face. In this course we learn how light is reflected, how a plane mirror forms an image, and how concave and convex mirrors form images that we can draw and also calculate.
5 lessons, about 2 h 20 min5 simulations14 problems10 practice questionsPython in every lesson
Created by StemPy LabA ray of light that falls on a smooth surface bounces back. The angle of incidence equals the angle of reflection, and the incident ray, the normal and the reflected ray lie in one plane. A plane mirror forms a virtual, upright image that is as big as the object and as far behind the mirror as the object is in front.
A spherical mirror is a part of a hollow sphere. A concave mirror reflects from the inside, and a convex mirror from the outside. Its pole, centre of curvature, radius of curvature, principal axis and principal focus describe it, and the focal length is half the radius of curvature.
The image in a concave mirror depends on where the object is. It can be real and inverted, smaller, equal or larger, when the object is beyond F. It is virtual, upright and larger when the object is between the pole and the focus. Concave mirrors are used in torches, headlights, shaving mirrors and solar cookers.
A convex mirror always forms a virtual, upright and smaller image behind the mirror, wherever the object is. It gives a wide field of view, so it is used as a rear-view mirror in vehicles and as a security mirror.
The New Cartesian sign convention gives each distance a sign. The mirror formula is , and the magnification is . With these we can find the position, size and nature of any image without drawing.
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