American Buddhismâs numbers are booming. Published just over three years ago, an American Religious Identification Survey survey showed that from the years 1990 to 2000, Buddhism grew 170 percent in North America.
However, for a lens, a positive image distance implies that the image is located on the opposite side as the object. Virtual images are formed by concave lenses or by placing an object inside the focal length of a convex lens. The ray-tracing exercise is repeated for the case of a virtual image. In this case the virtual image is upright and shrunken. The same formula for the image and object distances used above applies again here.
The concave convex is used as the objective lens that is aligned with the eyepiece and with the convex side facing the sky. Notice that this lens is actually different than the plano convex lens used in the original Galilean telescope, but still gives the same results. The following design uses pieces of the inner tube of the mailing tube to hold the lenses in place inside the outer tube.