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Difficulty: MediumThin Lenses, Optical Instruments, and Defects of Vision

Match each optical instrument component or device on the left with its correct focal length requirement and image formation condition on the right.

  • Compound Microscope Objective LensVery short focal length producing a real, inverted, and magnified intermediate image
  • Astronomical Telescope Objective LensLong focal length forming a real, inverted, and diminished image of a distant body
  • Simple Magnifying GlassSingle convex lens with object placed within focal length producing an erect, virtual, and magnified image
  • Slide / Film Projector LensConvex lens with object positioned between ff and 2f2f producing a real, inverted, and enlarged image on a screen

Answer

Compound Microscope Objective Lens pairs with very short focal length producing a real, inverted, and magnified intermediate image. Astronomical Telescope Objective Lens pairs with long focal length forming a real, inverted, and diminished image of a distant body. Simple Magnifying Glass pairs with single convex lens with object placed within focal length producing an erect, virtual, and magnified image. Slide / Film Projector Lens pairs with convex lens with object positioned between f and 2f producing a real, inverted, and enlarged image on a screen.
The matching correct pairs align each optical device with its precise optical parameter: microscope objectives utilize short focal lengths for high magnification of near objects, telescope objectives utilize long focal lengths for distant objects, simple magnifiers place objects closer than the focal point to form virtual erect images, and projectors place objects between one and two focal lengths to cast real enlarged images on a screen.

Step-by-Step Solution

1
Analyze the objective lens of a compound microscope
It requires a very short focal length to achieve high linear magnification of near objects.
The specimen is placed just outside the focal point (f<u<2ff < u < 2f), producing a real, inverted, magnified image inside the tube.
2
Analyze the objective lens of an astronomical telescope
It requires a long focal length and large aperture.
Distant celestial bodies subtend tiny angles at the eye; a long focal length objective creates a larger real intermediate image for the eyepiece to magnify.
3
Analyze the ray path condition of a simple magnifying glass
The object is held within the principal focus (u<fu < f).
Light rays emerging from the lens diverge, forming an enlarged, virtual, and erect image on the same side of the lens as the object.
4
Analyze the image projection setup in a slide projector
The slide is placed between ff and 2f2f of a converging lens.
According to the thin lens formula, placing an object between ff and 2f2f yields a real, inverted, magnified image beyond 2f2f.

Key Concept

Operating principles and ray placement parameters of optical instruments
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Topics

Thin Lenses, Optical Instruments, and Defects of Vision

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