Draw a ray diagram of compound microscope, when the final image is formed at the minimum distance of distinct vision.

To understand how a compound microscope works, especially when the final image is formed at the minimum distance of distinct vision (usually around 25 cm for a human eye), let's break down the ray diagram and the principles behind it.

Components of a Compound Microscope

A compound microscope consists of two main lenses: the objective lens and the eyepiece (or ocular lens). The objective lens is positioned close to the specimen, while the eyepiece is where the viewer looks through. The combination of these lenses magnifies the image of the specimen.

Ray Diagram Explanation

When drawing a ray diagram for a compound microscope, we need to consider the following steps:

• Step 1: Position the Objective Lens - The objective lens is placed at a distance from the specimen. For our diagram, let’s assume the object (specimen) is placed just within the focal length of the objective lens.
• Step 2: Draw the Object - Represent the object as an arrow pointing upwards. This object is typically smaller than the image formed.
• Step 3: Rays from the Object - Draw two principal rays from the top of the object:
  • The first ray travels parallel to the principal axis and then refracts through the focal point on the opposite side of the lens.
  • The second ray passes through the center of the objective lens without bending.
• Step 4: Locate the Image Formed by the Objective Lens - The intersection of the refracted rays gives the position of the real, inverted image formed by the objective lens. This image acts as the object for the eyepiece.
• Step 5: Position the Eyepiece - The eyepiece is placed such that the real image formed by the objective lens is within its focal length.
• Step 6: Draw Rays from the Objective Image - Similar to the previous step, draw two rays from the top of the real image:
  • One ray travels parallel to the principal axis and refracts through the focal point of the eyepiece.
  • The second ray passes through the center of the eyepiece lens.
• Step 7: Determine the Final Image - The rays from the eyepiece will diverge, and when extended backward, they appear to originate from a point. This point is where the final virtual image is formed, which is upright and magnified.

Final Image at Minimum Distance of Distinct Vision

When the final image is formed at the minimum distance of distinct vision (25 cm), it means that the virtual image created by the eyepiece is positioned at this distance from the eye. This allows for comfortable viewing without straining the eye.

Visualizing the Diagram

In a typical ray diagram, you would see:

• The object on the left, with rays diverging from it.
• The objective lens in the center, creating an inverted image.
• The eyepiece on the right, where the rays diverge to form a virtual image.

By following these steps, you can create a clear ray diagram that illustrates how a compound microscope magnifies an object, especially when the final image is positioned at the minimum distance of distinct vision. This understanding is crucial for grasping the functionality of optical instruments in biology and other sciences.