Answer: 20 years. Furnaces should last between 15 and 20 years, according to industry experts and the Department of Energy. Furnace filters, however, only hold up one to three months â and in order to avoid an expensive service call, it's crucial to change them on the manufacturer's schedule.
Lens Improvement. Later in the 16th century, Anton van Leeuwenhoek began polishing and grinding lenses when he discovered that certain shaped lenses increased an imageâs size. The glass lenses that he created could enlarge an object many times.
Electron Microscopes: In 1931 Max Knoll and Ernst Ruska invented the first electron microscope that blasted past the optical limitations of the light. Physics dictates that light microscopes are limited by the physics of light to 500x or 1000x magnification and a resolution of 0.2 micrometers.lectron Microscopes: In 1931 Max Knoll and Ernst Ruska invented the first electron microscope that blasted past the optical limitations of the light. Physics dictates that light microscopes are limited by the physics of light to 500x or 1000x magnification and a resolution of 0.2 micrometers.