You can also lodge a telephone complaint while you are in Australia by ringing the Australian Consumer Affairs and Fair Trading Hotline 1300 552 263 (local call cost within Australia). The call will be automatically forwarded to the fair trading agency in the state or territory from which you are calling.
Circular paraboloid. A parabolic (or paraboloid or paraboloidal) reflector (or dish or mirror) is a reflective surface used to collect or project energy such as light, sound, or radio waves. Its shape is part of a circular paraboloid, that is, the surface generated by a parabola revolving around its axis. The parabolic reflector transforms an incoming plane wave traveling along the axis into a spherical wave converging toward the focus.
As is easily demonstrated, in the paraxial approximation, the focal length of a convex mirror is half of its radius of curvature. Figure 74: The virtual focus of a convex mirror. There are, again, two alternative methods of locating the image formed by a convex mirror. The first is graphical, and the second analytical. According to the graphical method, the image produced by a convex mirror can always be located by drawing a ray diagram according to four simple rules: 1  An incident ray which is parallel to the principal axis is reflected as if it came from the virtual focus of the mirror.