Optics & Waves · GCSE Physics Topic 6
Pinhole Camera & Eclipse Simulator
Key exam takeaway: Pinhole image shape depends solely on the source object, not the hole shape. Dappled circular sunspots beneath trees are real images of the sun.
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- Live Derivation
- Projector Mode
- Print Worksheet
3D Simulation Stage● 60 FPS
Parameter Controls
cm
cm
mm
Live Derivations & Metrics
Image Magnification M
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Image Quality & Reality
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Image Orientation
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Astronomical Eclipse Mode
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Real-Time Formula Derivation
Governing Formula:
--Substitution:
--Regime: --
Worked Examples & Exam Question Deep Dive
Worked Problem
Problem: A 6cm candle is 10cm from pinhole, screen is 25cm away. Find image height and nature.
Step-by-Step Derivation:
- By similar triangles: H / 6 = 25 / 10 => H = 15cm. The image is inverted, magnified and real.
Worked Problem
Problem: Under sunny tree canopy, circular spots cover the ground. What are they? What shape during partial solar eclipse?
Step-by-Step Derivation:
- Circular patches are pinhole images of the round sun. During a partial solar eclipse, they all turn into crescents.
Student Inquiry Worksheet & Practice Problems
Q1. Variant 1: Does pinhole inversion also flip left and right? How to verify experimentally?
Answer Key: Yes! Pinhole inversion is a 180° point reflection (central inversion), flipping both top/bottom and left/right.
Q2. Variant 2: What is the spatial alignment order of Sun, Earth, and Moon during solar and lunar eclipses?
Answer Key: Solar eclipse: Sun - Moon - Earth (Moon shadows Earth). Lunar eclipse: Sun - Earth - Moon (Earth shadows Moon).
Q3. Variant 3: What is the speed of light in vacuum? Is it faster or slower in water and glass?
Answer Key: Vacuum speed c ≈ 3.0*10^8 m/s. In water (2.25*10^8 m/s) and glass (2.0*10^8 m/s), light travels slower since v = c/n.
Frequently Asked Questions & Misconceptions
Why is a pinhole camera image always a real image?
Real images are formed by intersecting actual light rays and can be captured on physical screens or photographic film.
Why does an excessively large aperture blur out the image?
A large hole acts like thousands of overlapping tiny pinholes, blurring individual inverted images into an unstructured illumination blob.
What distinguishes total, annular, and partial solar eclipses?
Total: observer in lunar umbra. Annular: in antumbra (golden ring left). Partial: in penumbra (crescent bite).
Why are there annular solar eclipses but no "annular lunar eclipses"?
Earth is much larger than the Moon; Earth's umbral shadow at the Moon is 2.7x Moon's diameter, completely enveloping it.