An electron microscope has a much greater useful magnification than an optical microscope because it can resolve smaller details. What makes the higher resolving power possible?

The higher resolving power of an electron microscope is made possible by several factors:

1. Wavelength: In an optical microscope, visible light is used to form an image, and its wavelength is limited to the range of 400 to 700 nanometers. On the other hand, an electron microscope uses a beam of electrons to form an image, and electrons have much shorter wavelengths, typically in the range of 0.0025 to 0.005 nanometers. The shorter wavelength of electrons allows them to interact with matter at a much finer scale, resulting in higher resolution.

2. Electromagnetic lens: To focus the electron beam and produce an image, electron microscopes use electromagnetic lenses rather than glass lenses used in optical microscopes. These lenses use electromagnetic fields to control and manipulate the path of the electron beam. Unlike glass lenses, electromagnetic lenses are not limited by the wavelength of light and can focus electrons with much greater precision, resulting in improved resolution.

3. Vacuum environment: Electron microscopes require a vacuum environment to prevent the scattering and absorption of electrons by air molecules. The absence of air allows the electrons to maintain their energy and focus better as they travel through the microscope, leading to sharper and more detailed images.

4. Electron detectors: Electron microscopes utilize highly sensitive detectors to capture the electrons that interact with the specimen. These detectors, such as scintillators or semiconductor-based sensors, convert the energy of the electrons into a signal that can be amplified and transformed into a digital image. The sensitivity of these detectors allows for the detection of even the faintest signals, enabling the visualization of small details and structures within the specimen.

By combining these factors, electron microscopes overcome the limitations of optical microscopes and achieve higher resolving power, enabling the visualization of smaller details in the nanometer range.