Optical Instruments
Physics ⇒ Light and Optics
Optical Instruments starts at 10 and continues till grade 12.
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A compound microscope has an objective of focal length 2 cm and an eyepiece of focal length 5 cm. If the object is placed 2.2 cm from the objective, calculate the magnifying power when the final image is formed at the least distance of distinct vision (25 cm).
A compound microscope is adjusted so that the final image is formed at infinity. What is the magnifying power in terms of the focal lengths of the objective (fo) and eyepiece (fe)?
A person is using a simple magnifier of focal length 10 cm. What is the maximum magnification possible if the least distance of distinct vision is 25 cm?
A person uses a convex lens of focal length 20 cm as a simple magnifier. If the object is placed at 15 cm from the lens, where is the image formed?
A telescope has an objective lens of focal length 100 cm and an eyepiece of focal length 5 cm. What is the magnifying power of the telescope when the final image is at infinity?
Describe the principle of a spectrometer.
Describe the working principle of a periscope.
Explain the difference between a refracting and a reflecting telescope.
Explain why astronomical telescopes use large objective lenses or mirrors.
Explain why binoculars are preferred over telescopes for terrestrial viewing.
In a laboratory, a student uses a spectrometer to measure the angle of minimum deviation for a prism. What property of the prism can be determined from this measurement?
Name the defect of vision in which a person cannot distinguish between certain colors.
State the function of the objective lens in a compound microscope.
A compound microscope uses an objective lens of focal length 1.5 cm and an eyepiece of focal length 4 cm. If the tube length is 16 cm and the final image is formed at infinity, calculate the total magnifying power of the microscope.
A reflecting telescope uses a concave mirror of diameter 1.2 m. If the wavelength of light used is 500 nm, calculate the theoretical angular resolution of the telescope.
A student observes that the image through a compound microscope is blurry at the edges but sharp at the center. Which optical aberration is most likely responsible for this effect?
Explain why the resolving power of a microscope is fundamentally limited by the wavelength of light used, and derive the expression for the minimum resolvable distance between two points.
In a laboratory experiment, a student uses a spectrometer to measure the angle of deviation for various wavelengths passing through a prism. Explain how this data can be used to determine the dispersive power of the prism material.
The numerical aperture (NA) of a microscope objective is defined as NA = n sinθ, where n is the refractive index of the medium and θ is the half-angle of the maximum cone of light that can enter the lens. If an oil immersion objective uses oil of refractive index 1.5 and θ = 60°, calculate the numerical aperture.
