Question

The light source in optical microscope is

• A. X-rays
• B. Natural light
• C. Electron beam
• D. Gamma rays

Hint:

The name of the microscope often tells you its illumination source. Optical/Light Microscope uses visible light. Electron Microscope uses an electron beam. X-ray Microscope uses X-rays.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
An optical microscope, also known as a light microscope, uses visible light and a system of lenses to magnify images of small samples. The question asks about the type of illumination source used.

Step 2: Detailed Explanation:
Let's analyze the different options provided:

X-rays: These are high-energy electromagnetic waves. They are used in X-ray microscopy and crystallography to determine atomic and molecular structures, not in standard optical microscopes.

Natural light: This refers to light from the sun or ambient room light. Early microscopes used mirrors to direct natural light onto the specimen. While modern microscopes typically use built-in artificial light sources (like halogen lamps or LEDs), these sources produce light in the visible spectrum, which is the same type of light as natural light. Among the given choices, "Natural light" or more broadly, visible light, is the correct type of radiation used for illumination.

Electron beam: A beam of electrons is used as the illumination source in Electron Microscopes (e.g., TEM, SEM). These microscopes can achieve much higher magnification and resolution than optical microscopes because the de Broglie wavelength of electrons is much shorter than that of visible light photons.

Gamma rays: These are the highest-energy form of electromagnetic radiation. They are not used for microscopy due to their extremely high energy and difficulty in focusing.
Based on the options, the fundamental source of illumination for an optical microscope is visible light. "Natural light" is a form of visible light and is the most plausible answer among the choices, representing the correct category of the electromagnetic spectrum.

Step 3: Final Answer:
Optical microscopes operate using visible light. Of the options provided, "Natural light" falls into this category and is the correct choice, distinguishing it from other forms of radiation used in different types of microscopes.