Compound microscope
"Compound microscope" is a free, interactive Class 12 Physics simulation for NEET and JEE, built on the NCERT section "Simple and compound microscope" in Ray Optics and Optical Instruments. The objective's real enlarged image magnified again by the eyepiece, to the near point or to infinity, with m = m_o × m_e. NEET has asked about this idea 1 time in 10 years of papers. JEE Main asked 66 questions from this chapter across the 42 shifts Lumi has analysed (2017–2026).
From the lesson Simple and compound microscope in Ray Optics and Optical Instruments. Change the values and watch what happens.
What it shows
NCERT § The Microscope
The objective's real enlarged image magnified again by the eyepiece, to the near point or to infinity, with m = m_o × m_e.
Controls
4 to try
- Sliderf_o 0.5–3 cm
- Sliderf_e 1–10 cm
- Slidertube length L 10–25 cm
- Togglefinal image at near point / infinity
Try this
Reach magnification 250 with the relaxed eye (e.g. L = 20 cm, f_o = 1 cm, f_e = 2 cm)
Common mistake
Mixing up the near-point (1 + D/f) and infinity (D/f) formulas.
In NEET
10 years of papers
Asked 1 time in 10 years of NEET.
See the past questions: Prisms, Dispersion and Optical Instruments, Ray Optics and Optical Instruments (chapter)
In JEE Main
42 shifts analysed
66 questions from Ray Optics and Optical Instruments across the 42 JEE Main shifts Lumi has analysed (2017–2026).
The idea behind it
NCERT § "The Microscope"
- A simple microscope (magnifier) is a converging lens of short focal length held close to the eye with the object within its focal length, giving a virtual, erect, enlarged image.
- Its angular magnification is m = 1 + D/f if the image forms at the near point (D = 25 cm), and m = D/f for an image at infinity (relaxed eye).
- A compound microscope has an objective of short focal length that forms a real, inverted, enlarged image, which the eyepiece then magnifies further as a simple microscope.
- Total magnification m = m_o × m_e. For the objective, the linear magnification is m_o = L/f_o, where L, the tube length, is measured from the objective's second focal point to the eyepiece's first focal point.
- With the final image at infinity, m = (L/f_o)(D/f_e); with the final image at the near point, the eyepiece contributes (1 + D/f_e).
- The final image in a compound microscope is inverted with respect to the object.
- High magnification needs short focal lengths for both objective and eyepiece.
Questions
5 answers
- What does the "Compound microscope" simulation show?
- The objective's real enlarged image magnified again by the eyepiece, to the near point or to infinity, with m = m_o × m_e.
- What mistake does the "Compound microscope" simulation fix?
- A common mistake it clears up: mixing up the near-point (1 + D/f) and infinity (D/f) formulas.
- Has NEET asked about this idea?
- Yes. NEET has asked about this idea 1 time in 10 years of papers.
- Does JEE Main ask questions from Ray Optics and Optical Instruments?
- Yes. JEE Main asked 66 questions from this chapter across the 42 shifts Lumi has analysed (2017–2026).
- Is this simulation free?
- Yes. It is free and runs in the browser on a phone or a laptop. It belongs to the lesson "Simple and compound microscope" in Ray Optics and Optical Instruments (Class 12 Physics).
Embed this simulation
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