Case Study:

In a district government hospital pathology lab, blood and tissue samples are examined daily to detect infections and abnormal cell growth. A compound microscope is used to observe the structure of cells on glass slides. The microscope has an objective lens of focal length 1 cm and an eyepiece of focal length 5 cm.

The technician adjusts the mirror and diaphragm to allow sufficient light to pass through the sample. When the light intensity is low, the cell boundaries appear unclear. Increasing illumination improves visibility but excessive light causes glare and loss of contrast.

During one test, the technician notices that at low magnification the nucleus is visible but finer structures are not clear. By switching to a higher power objective lens, the image becomes larger but slightly blurred. Proper focusing and correct distance between the lenses help achieve a sharp image.

The doctor explains that if the microscope does not produce a clear image, the diagnosis may be delayed or incorrect. Thus, understanding how magnification and light affect image formation is important for accurate observation of cell structure in pathology labs.

Questions:

Section A - MCQs 

1. The reason finer cell details are seen better at higher magnification is because:
A. The image becomes brighter
B. The image size increases
C. The object moves closer
D. The light speed increases

2. Blurring of image at high magnification mainly occurs due to:
A. Low focal length
B. Poor illumination and improper focusing
C. High temperature
D. Dust in air

3. Which adjustment improves image contrast in the microscope?
A. Increasing object distance
B. Changing slide thickness
C. Adjusting diaphragm for light control
D. Reducing lens power

4. The eyepiece mainly helps in:
A. Forming real image
B. Increasing brightness
C. Magnifying the image formed by objective lens
D. Holding the slide

Section B - Short Answer Questions

1. Why is proper illumination necessary for observing cell structure clearly?
2. How does increasing magnification affect image clarity?
3. Explain why correct focusing is important in a pathology lab.

Section C – Long Answer Question (1 question)

1. A microscope in a pathology lab gives a blurred image of cells even at high magnification.
(a) State two possible reasons for this problem.
(b) Suggest two corrective measures.
(c) Explain how this affects medical diagnosis.

Answer Key:

MCQs:

1. B
2. B
3. C
4. C

Short Answers:

1. Proper illumination allows light to pass clearly through the sample, making cell boundaries and structures visible.
2. Increasing magnification enlarges the image but may reduce clarity if light and focus are not properly adjusted.
3. Correct focusing ensures the image is sharp and prevents misinterpretation of cell structure.

Long Answer:

(a) Reasons: poor illumination, improper focusing, or dirty lenses.
(b) Measures: adjust diaphragm and mirror, clean lenses, and refocus properly.
(c) Blurred images may hide cell abnormalities, leading to wrong or delayed diagnosis.