A condenser is an optical lens which renders a divergent beam from a point source into a parallel or converging beam to illuminate an object.
Condensers are an essential part of any imaging device, such as microscopes, enlargers, slide projectors, and telescopes. The concept is applicable to all kinds of radiation undergoing optical transformation, such as electrons in electron microscopy, neutron radiation and synchrotron radiation optics.
Need help with Coil and Capacitor
In a circuit with AC voltage and serial coupling of a coil and a capacitor, there is supposed to be a "resonance" frequency of some kind. Can anyone explain this and a solution?