Chapter 10: Optical Instruments - Key Topics MCQS
Chapter 10: Optical Instruments - Key Topics
Below are 10 Multiple Choice Questions (MCQs) with answers and brief explanations, specifically from Chapter 10: Optical Instruments of the FBISE (Federal Board of Intermediate and Secondary Education) 11th-class Physics syllabus for the 2025 exam. These MCQs are designed to align with the FBISE syllabus, focusing on key concepts such as lenses, microscopes, telescopes, and their magnifying power, as outlined in the official curriculum and reflected in past papers and resources like www.taleemcity.com and www.ilmistarsacademy.com. They are crafted to match the style and difficulty level of FBISE exams.
Chapter 10: Optical Instruments - Key Topics
- Lenses: Convex and concave lenses, lens formula.
- Simple Microscope: Magnifying power, image formation.
- Compound Microscope: Structure, magnification.
- Astronomical Telescope: Normal adjustment, magnifying power.
- Spectrometer: Function and components.
- Applications: Ray diagrams, lens combinations.
10 MCQs with Answers and Explanations
- Question: The lens formula is given by:
- A) 1/f = 1/u + 1/v
- B) 1/f = 1/u - 1/v
- C) 1/f = 1/v - 1/u
- D) 1/f = u + v
- Answer: A) 1/f = 1/u + 1/v
- Explanation: The lens formula relates the focal length (f), object distance (u), and image distance (v) for thin lenses, used in optical instruments.
- Question: In a simple microscope, the magnifying power is maximum when the image is formed at:
- A) Infinity
- B) The focal point
- C) The near point
- D) The far point
- Answer: C) The near point
- Explanation: The magnifying power of a simple microscope is M = 1 + D/f (where D is the near point, typically 25 cm), maximized when the image is at the near point.
- Question: The objective lens of a compound microscope has:
- A) Long focal length
- B) Short focal length
- C) Zero focal length
- D) Variable focal length
- Answer: B) Short focal length
- Explanation: The objective lens has a short focal length to produce a large, real, and inverted image close to the eyepiece.
- Question: The final image formed by a compound microscope is:
- A) Real and erect
- B) Virtual and inverted
- C) Real and inverted
- D) Virtual and erect
- Answer: B) Virtual and inverted
- Explanation: The compound microscope’s objective forms a real, inverted image, which the eyepiece magnifies into a virtual, inverted final image.
- Question: In an astronomical telescope in normal adjustment, the final image is formed at:
- A) The focal point of the objective
- B) The near point
- C) Infinity
- D) The eyepiece’s focal point
- Answer: C) Infinity
- Explanation: In normal adjustment, the telescope’s intermediate image is at the focal point of the objective, and the eyepiece forms the final image at infinity for relaxed viewing.
- Question: The magnifying power of an astronomical telescope in normal adjustment is:
- A) f_o / f_e
- B) f_e / f_o
- C) f_o + f_e
- D) f_o × f_e
- Answer: A) f_o / f_e
- Explanation: Magnifying power M = f_o / f_e, where f_o is the focal length of the objective and f_e is the focal length of the eyepiece.
- Question: A spectrometer is used to:
- A) Measure the speed of light
- B) Analyze the spectrum of light
- C) Magnify distant objects
- D) Measure lens focal length
- Answer: B) Analyze the spectrum of light
- Explanation: A spectrometer disperses light into its spectrum to study wavelengths, using components like a collimator, prism, and telescope.
- Question: In a compound microscope, if the focal length of the eyepiece is increased, the magnifying power:
- A) Increases
- B) Decreases
- C) Remains the same
- D) Becomes zero
- Answer: B) Decreases
- Explanation: Magnifying power M ≈ (L/f_o)(D/f_e), where f_e is the eyepiece focal length. Increasing f_e reduces M.
- Question: The role of the collimator in a spectrometer is to:
- A) Disperse light
- B) Produce parallel rays
- C) Magnify the image
- D) Focus light on the eyepiece
- Answer: B) Produce parallel rays
- Explanation: The collimator converts divergent light into a parallel beam, which is then dispersed by the prism or grating.
- Question: A convex lens of focal length 10 cm is used as a simple microscope. The magnifying power when the image is at the near point (D = 25 cm) is:
- A) 2.5
- B) 3.5
- C) 4.5
- D) 5.5
- Answer: B) 3.5
- Explanation: Magnifying power M = 1 + D/f = 1 + 25/10 = 1 + 2.5 = 3.5.
Key Notes
- Syllabus Alignment: These MCQs cover core topics from Chapter 10 (Optical Instruments) of the FBISE 11th-class Physics syllabus, including lenses, microscopes, telescopes, and spectrometers, which are frequently tested in exams.
- Question Variety: The questions include conceptual, numerical, and application-based MCQs to reflect FBISE’s exam pattern, with emphasis on magnifying power and lens properties.
- Explanations: Brief explanations clarify the reasoning, aiding quick understanding and revision.
Recommended Resources for Additional MCQs
For more MCQs on Chapter 10 (Optical Instruments):
- FBISE Official Website (www.fbise.edu.pk):
- Access past papers (2016–2024) under “Examinations” > “Past Papers.” Chapter 10 MCQs appear in the objective section.
- Taleem City (www.taleemcity.com):
- Offers solved MCQs for Chapter 10 in PDF format, tailored for FBISE syllabus.
- Ilmi Stars Academy (www.ilmistarsacademy.com):
- Provides chapter-specific MCQs with answers and video explanations.
- Download Class Notes (www.downloadclassnotes.com):
- Contains solved MCQs for Optical Instruments in downloadable PDFs.
- Pak Learning Spot (www.paklearningspot.com):
- Features free MCQs for FBISE board exams, including Chapter 10.
How to Access:
- Visit these websites, navigate to the 11th-class Physics section, and select “Chapter 10 MCQs” or “Optical Instruments.”
- Past papers are available on the FBISE website in PDF format, free of charge.
Tips for MCQ Preparation
- Focused Practice: Solve 10–15 MCQs daily for Chapter 10 to master concepts like magnifying power and lens formulas.
- Time Yourself: Aim for ~1 minute per MCQ to build exam speed.
- Review Errors: Use answer keys to understand mistakes and revisit concepts like telescope adjustment or microscope magnification.
- Combine with Diagrams: Pair MCQ practice with studying ray diagrams (e.g., compound microscope, telescope) from the FBISE textbook (available on www.taleem360.com).
Additional Support
These 10 MCQs are tailored to support your preparation for the 2025 FBISE exam. If you need:
- More MCQs for Chapter 10 (Optical Instruments).
- MCQs for other chapters or specific topics (e.g., telescope, spectrometer).
- Assistance downloading resources or solving numericals. please let me know, and I’ll provide further tailored support. Good luck with your Physics exam preparation!
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