Converging Lenses
Thicker in the middle, converge light rays to form real images when rays cross, unless the object is at the focal point or nearer.
Diverging Lenses
Thinner in the middle, diverge light rays, forming virtual images where rays appear to have come from.
Focal Point
Where parallel rays converge or appear to diverge after passing through the lens.
Optical Power
Measured in diopters (D), defined as the inverse of focal length (P = 1/f).
Real Images
Form where rays converge.
Virtual Images
Form where rays appear to diverge.
Magnification
Calculated as the ratio of image height to object height (m = hi/ho = -v/u).
Spherical Aberration
Causes distorted images due to the lens's inability to focus all rays at the same point.
Chromatic Aberration
Results from the lens's inability to bring rays of different colors to the same focus.
Radio Telescopes
Experience less atmospheric interference, enhancing resolution through interferometry techniques.
Resolution
The ability to distinguish separate points, often more critical than magnification.
Reflecting Telescopes
Use converging mirrors as their objectives.
Fiber Optics
Offer advantages over copper, including lower attenuation and immunity to electromagnetic interference.
Ultrasound Imaging
Uses wave propagation and reflection to create images of body tissues.
Magnetic Resonance Imaging (MRI)
Utilizes proton spin resonance in strong magnetic fields to produce three-dimensional images.