AIIMS2019Physics-Optics

AIIMS 2019 Physics Microscope MCQ Question

Type: MCQ-conceptual-Medium-Class 12

If f0=5 cm\text{f}_0 = 5 \text{ cm}, λ=6000A˚\lambda = 6000\text{\AA}, a=1 cm\text{a} = 1 \text{ cm} for a microscope, then what will be its resolving power.

A

11.9×105/m11.9 \times 10^5 /\text{m}

B

10.9×105/m10.9 \times 10^5 /\text{m}

C

10.9×105/m10.9 \times 10^5 /\text{m}

D

10.9×103/m10.9 \times 10^3 /\text{m}

Correct Answer

Option B

Detailed Explanation

Option B correctly calculates the resolving power (RP) of a microscope using the formula RP=2μsinθ1.22λRP = \frac{2\mu \sin \theta}{1.22 \lambda}, where μ\mu is the refractive index (assumed to be 1 for air), θ\theta is the angle of the lens, and λ\lambda is the wavelength of light (given as 6×1076 \times 10^{-7} m). Substituting sinθ\sin \theta with 0.20.2 yields an RP of approximately 10.9×105m110.9 \times 10^5 \, \text{m}^{-1}, demonstrating the microscope's ability to distinguish between closely spaced objects.

Option A incorrectly equates tanθ\tan \theta and sinθ\sin \theta without considering the small angle approximation, which is only valid for small angles. Options C and D are not applicable, as they do not provide relevant information or calculations. Understanding the relationship between angle, wavelength, and resolving power is crucial for optimizing microscope performance.

Found an issue with this question?