Exams › JEE Advanced › Physics

A microscope has a numerical aperture (NA) of 1.25 and uses light of wavelength 500 nm. Which of the following statements about its resolving power are correct?

1. Decreasing the wavelength of light used will increase the resolving power, allowing the microscope to distinguish smaller structures.
2. Increasing the numerical aperture of the objective lens will improve the resolving power, reducing the minimum resolvable distance between two points.
3. Using an immersion oil with a higher refractive index will improve the resolving power.
4. Using light of wavelength 1000 nm will improve the resolving power of the microscope.

Correct answer: Decreasing the wavelength of light used will increase the resolving power, allowing the microscope to distinguish smaller structures.

Solution

The minimum resolvable distance: d = 0.61*lambda/NA. Higher resolving power means smaller d. Statement A: decreasing lambda decreases d — correct. Statement B: increasing NA decreases d — correct. Statement C: immersion oil with higher refractive index increases NA (since NA = n*sin(theta)), which decreases d — correct. Statement D: using 1000 nm (longer wavelength) increases d, so resolving power decreases — incorrect. All of A, B, C are correct. However, if this is a single-correct MCQ, statement A is the most directly stated correct one. The question says 'which are correct' (multiple correct possible). A, B, C are all correct.

Related JEE Advanced Physics questions

• What factor influences the visibility of fringes in an interference pattern?
• When the screen is moved further along the x-axis away from the source, which of the following statements is false?
• In the Young's double slit experiment using a monochromatic light of wavelength λ, the path difference (in terms of an integer n) corresponding to any point having half the peak intensity is
• Using the expression 2d sin θ = λ, one calculates the values of d by measuring the corresponding angles θ in the range 0 to 90°. The wavelength λ is exactly known and the error in θ is constant for all values of θ. As θ increases from 0°:
• Two coherent point sources separated by a distance d = 5 micrometers emit light of wavelength lambda = 2 micrometers in phase. A circular wire of radius R = 20 micrometers is placed symmetrically around the two sources (sources lie along a diameter). Points A and B are at the ends of the diameter along the line joining the sources; points C and D are at the ends of the diameter perpendicular to the line joining the sources. Which of the following is correct?
• Young's double slit experiment is performed in a medium of refractive index mu1 = 4/3. A thin transparent slab of refractive index mu2 = 3/2 and thickness t = 8 micrometers is placed in front of slit S2. The magnitude of the optical path difference (with respect to the liquid medium) at the central point O is:

⚔️ Practice JEE Advanced Physics free + battle 1v1 →