Question

Which of the following is correct about resolving power of a Microscope ? A. Limit of Resolution is directly proportional to the numerical aperture.
B. Resolution power of a microscope increases with magnification.
C. The greatest resolution in light microscopy is obtained with the shortest wavelength of light.
D. Limit of resolution is the smallest distance by which two objects can be separated and still be distinguishable.
E. The maximum resolution of a light microscope is \(0.02\, \mu m\).
Choose the correct answer from the options given below :

• A. \(A\) only
• B. \(C \text{ and } D\) only
• C. \(B\) only
• D. \(D \text{ and } E\) only

Hint:

Remember the resolution formula: \[ d = \frac{0.61\lambda}{NA} \] Better resolution occurs with:
• Smaller wavelength
• Higher numerical aperture \[ \text{Light microscope resolution} \approx 0.2\, \mu m \]

Answer 1

The Correct Option is B

Concept: The resolving power of a microscope is its ability to distinguish two closely spaced objects as separate entities. The limit of resolution is given by: \[ d = \frac{0.61\lambda}{NA} \] where:
• \(d\) = limit of resolution
• \(\lambda\) = wavelength of light
• \(NA\) = numerical aperture Better resolution means: \[ \text{Smaller value of } d \]

Step 1: Evaluating statement A. Statement A: \[ \text{Limit of resolution is directly proportional to numerical aperture} \] From the formula: \[ d \propto \frac{1}{NA} \] Thus, limit of resolution is inversely proportional to numerical aperture. Therefore: \[ \boxed{A \text{ is incorrect}} \]

Step 2: Evaluating statement B. Statement B: \[ \text{Resolution increases with magnification} \] This is incorrect. Magnification enlarges the image but does not necessarily improve resolving power. Thus: \[ \boxed{B \text{ is incorrect}} \]

Step 3: Evaluating statement C. Statement C: \[ \text{Greatest resolution is obtained with shortest wavelength} \] This is correct because: \[ d \propto \lambda \] Shorter wavelength gives smaller \(d\) and therefore better resolution. Thus: \[ \boxed{C \text{ is correct}} \]

Step 4: Evaluating statement D. Statement D: \[ \text{Limit of resolution is the minimum distinguishable distance} \] This is the correct definition of limit of resolution. Thus: \[ \boxed{D \text{ is correct}} \]

Step 5: Evaluating statement E. Statement E: \[ \text{Maximum resolution of light microscope is }0.02\,\mu m \] This is incorrect. Typical resolution limit of a light microscope is approximately: \[ 0.2\, \mu m \] Thus: \[ \boxed{E \text{ is incorrect}} \] Therefore, the correct statements are: \[ \boxed{C \text{ and } D} \] Hence, the correct answer is: \[ \boxed{(B)\ C \text{ and } D \text{ only}} \]