diverging lens การใช้

• Converging lenses have positive optical power, while diverging lenses have negative power.
• The distance found is the ( negative ) focal length of the diverging lens.
• The focal length " f " is positive for converging lenses, and negative for diverging lenses.
• Light from a laser is expanded by a diverging lens ( not shown ), then is collimated into a parallel beam.
• A point source of monochromatic light is expanded by a diverging lens ( not shown ), then is collimated into a parallel beam.
• *Whenever we look through a diverging lens ( one that is thicker at the edges than the middle ) or into a convex mirror, we see a virtual image.
• Aside from reflection off solid surfaces, the 1 / r?law can be modified by temperature gradients above the ground, which can act as a converging or diverging lens.
• Telephoto is designated because the longer focal length supplied by the negative diverging lens is longer than the overall lens assembly ( the negative diverging lens acting as the " telephoto group " ).
• Telephoto is designated because the longer focal length supplied by the negative diverging lens is longer than the overall lens assembly ( the negative diverging lens acting as the " telephoto group " ).
• With diverging lenses, incoming parallel rays diverge after going through the lens, in such a way that they seem to have originated at a spot one focal length in front of the lens.
• For presbyopia and hyperopia, a converging lens provides the extra curvature necessary to bring the near point closer to the eye while for myopia a diverging lens provides the curvature necessary to send the far point to infinity.
• The optical power of corrective lenses is measured in diopters, a value equal to the reciprocal of the focal length measured in metres; with a positive focal length corresponding to a converging lens and a negative focal length corresponding to a diverging lens.
• When this is achieved, the screen is replaced with a mirror and the diverging lens is inserted between the converging lens and the light source at such a distance to the mirror that the light returning through the diverging and converging lenses produces a sharp image on top of the luminous object.
• One special application is to determine the focal length of a diverging lens : A light source is placed at twice the focal length of a converging lens on one side and a screen at the same distance on the other side so that the image of the light source is the sharpest possible.