What does the Rayleigh Criterion describe?

A. The maximum intensity of light in a diffraction pattern

B. The speed of light in different mediums

C. The minimum separation between two point sources that can be resolved

D. The angle of incidence in a prism

Which factor does NOT directly affect the resolution of an optical instrument?

A. Wavelength of light used

B. Aperture size of the instrument

C. Distance between the object and the instrument

D. Refractive index of the medium

What is the primary limitation that prevents optical microscopes from resolving atomic structures?

A. Mechanical vibrations

B. Diffraction of light

C. Refraction of light

D. Absorption of light

In terms of resolution, what happens when the aperture size of an optical instrument is increased?

A. Resolution decreases

B. Resolution increases

C. Resolution remains the same

D. Resolution becomes infinite

According to the Rayleigh Criterion, two point sources are just resolvable when:

A. The central maximum of one coincides with the first minimum of the other

B. The central maximum of one coincides with the central maximum of the other

C. The first minimum of one coincides with the first minimum of the other

D. The two point sources are at least one wavelength apart

a) Explain the Rayleigh Criterion and its significance in determining the resolution of optical instruments. [3]

b) A telescope has an objective lens diameter of 2.5 m. If it is used to observe a star emitting light of wavelength 550 nm, calculate the minimum angular separation between two stars that the telescope can resolve. [4]

a) Describe the phenomenon of diffraction limit in the context of optical resolution. [3]

b) If an optical microscope has a numerical aperture of 1.25 and is used with light of wavelength 450 nm, determine its resolution limit. [3]

a) Explain how thin films can lead to both constructive and destructive interference of light. [3]

b) A soap bubble appears green (wavelength = 530 nm) when illuminated with white light. If the refractive index of the soap is 1.33, calculate the minimum thickness of the bubble that results in this observed colour. [4]

a) Explain the significance of the Rayleigh Criterion in determining the resolution of optical systems. [3]

b) A double slit experiment is set up with a slit separation of 0.5 mm and is illuminated with light of wavelength 600 nm. Calculate the angular width of the central maximum on a screen placed 2 m away. [3]

c) How would the angular width change if the wavelength of the light used is increased? [2]

a) Describe the phenomenon of thin film interference. [3]

b) A film of oil on water appears to have a blue hue when illuminated with white light. If the blue light has a wavelength of 470 nm and the refractive index of the oil is 1.45, determine the minimum thickness of the oil film. [4]

c) How would the observed colour change if the thickness of the oil film is increased? [2]