Question

The change of source of illumination from light to electrons significantly improved the \(\underline{\hspace{2cm}}\) of the microscope. 
 

• A. Resolving power
• B. Resolution
• C. Numerical aperture
• D. Magnification

Hint:

Think of it this way: Resolution/Resolving Power is about clarity, while Magnification is about size. You can magnify a blurry image, but it just gets bigger and blurrier. The switch to electrons improved the fundamental clarity (resolving power), which then made higher magnifications meaningful.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
The question asks which property of a microscope was most fundamentally improved by switching from using photons (light) to electrons as the illumination source.

Step 2: Detailed Explanation:
The ability of a microscope to distinguish between two closely spaced points is known as its resolving power or resolution. This ability is fundamentally limited by the wavelength of the illumination used. The relationship is described by the Abbe diffraction limit, which states that the minimum resolvable distance (d) is proportional to the wavelength (\(\lambda\)). \[ d \propto \lambda \] Electrons have a much shorter de Broglie wavelength than photons of visible light. By switching from light to electrons, the wavelength (\(\lambda\)) of the illumination source was reduced by several orders of magnitude. This dramatically decreased the minimum resolvable distance (d), thereby significantly increasing the microscope's ability to see fine details. This ability is called resolving power.
While magnification was also increased, the improvement in magnification is only useful if the resolving power is high enough to make the magnified details clear. The primary, limiting factor that was overcome was resolution. Resolving power is the direct measure of this ability.

Step 3: Final Answer:
The change of source of illumination from light to electrons significantly improved the resolving power of the microscope.