Question

In a simple microscope, .............

• A. a lens with negative power is used
• B. the focal length of the lens is less than the least distance for clear vision
• C. the focal length of the lens is greater than the least distance for clear vision
• D. magnification depends only on the focal length of the lens

Hint:

In a simple microscope, the lens has a positive focal length, and the focal length is greater than the least distance for clear vision. This creates magnification.

Answer 1

The Correct Option is B

Step 1: Understanding the simple microscope.
In a simple microscope, the lens is typically a convex lens. The focal length of the lens is greater than the least distance for clear vision, allowing for magnification of objects. The magnification increases as the focal length of the lens increases.
Step 2: Analyzing the options.
(A) a lens with negative power is used: Incorrect — Negative power would imply a concave lens, which is not typically used in simple microscopes.
(B) the focal length of the lens is less than the least distance for clear vision: Incorrect — This would result in a diminished image.
(C) the focal length of the lens is greater than the least distance for clear vision: Correct — This is the defining characteristic of a simple microscope, which provides magnification.
(D) magnification depends only on the focal length of the lens: Incorrect — While magnification is related to the focal length, other factors also affect it.
Step 3: Conclusion.
The correct answer is (C) the focal length of the lens is greater than the least distance for clear vision, which defines how a simple microscope works.