Compound Microscope
A compound microscope achieves high magnification by combining two convex lenses, and a laboratory student wants to know how its total magnification is built up.
Select the correct option:
Solution
The objective magnification multiplies the eyepiece magnification
In a compound microscope, NCERT describes a two-stage process in which the objective lens first forms a real, magnified, inverted image of the tiny object, and the eyepiece then acts as a simple magnifier on that intermediate image. Because the eyepiece further enlarges the already enlarged image, the total magnification is the product of the two individual magnifications, M=mo×me. This multiplicative build-up is what lets a microscope reach magnifications of hundreds or thousands, far beyond what either lens could achieve alone. The option that the magnifications add is wrong because stacking two enlargement stages multiplies rather than sums their effects. The option that only the eyepiece matters is wrong because the objective creates the crucial first enlarged image that the eyepiece then works on. The option that they subtract is wrong because both lenses enlarge, so their contributions reinforce rather than oppose. As stated in NCERT Class 12, Chapter 9, the microscope's total magnification equals the product of objective and eyepiece magnifications. A consistency check confirms that modest individual factors, say 10 and 10, multiply to a large overall 100, matching typical microscope performance.
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About This Question
- Subject
- physics
- Chapter
- optics
- Topic
- compound microscope
- Difficulty
- Medium
- Year
- 2025
Solution
Correct Answer:
The objective magnification multiplies the eyepiece magnification
In a compound microscope, NCERT describes a two-stage process in which the objective lens first forms a real, magnified, inverted image of the tiny object, and the eyepiece then acts as a simple magnifier on that intermediate image. Because the eyepiece further enlarges the already enlarged image, the total magnification is the product of the two individual magnifications, M=mo×me. This multiplicative build-up is what lets a microscope reach magnifications of hundreds or thousands, far beyond what either lens could achieve alone. The option that the magnifications add is wrong because stacking two enlargement stages multiplies rather than sums their effects. The option that only the eyepiece matters is wrong because the objective creates the crucial first enlarged image that the eyepiece then works on. The option that they subtract is wrong because both lenses enlarge, so their contributions reinforce rather than oppose. As stated in NCERT Class 12, Chapter 9, the microscope's total magnification equals the product of objective and eyepiece magnifications. A consistency check confirms that modest individual factors, say 10 and 10, multiply to a large overall 100, matching typical microscope performance.
This medium difficulty physics question is from the chapter optics, covering the topic of compound microscope. It appeared in the 2025 exam.
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